Method for improving enzyme activities with noble gases

ABSTRACT

A method for regulating enzyme activity, which entails contacting one or more enzymes with a gas containing one or more noble gases or mixtures thereof. The activity of an enzyme on a substrate can be improved by contacting the enzyme with a noble gas under specific temperatures and pressures. The preferred noble gases are krypton, neon, xenon, argon or mixtures of these gases. The enzymes whose activity can be improved are hydrolases, lyases, isomerases and ligases.

This application is a Continuation of application Ser. No. 07/706,587,filed on May 28, 1991, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for regulating enzymeactivities by noble gases.

2. Description of the Background

The ability of the noble gases helium (He), neon (Ne), argon (Ar),krypton (Kr), xenon (Xe) and radon (Ra) to enter into chemicalcombination with other atoms is extremely limited. Generally, onlykrypton, xenon and radon have been induced to react with other atoms,such as fluorine and oxygen, and the compounds thus formed areexplosively unstable. See Advanced Inorganic Chemistry, by F. A. Cottonand G. Wilkinson (Wiley, Third Edition). However, while the noble gasesare, in general, chemically inert, xenon is known to exhibit certainphysiological effects, such as anesthesia. Other physiological effectshave also been observed with other inert gases such as nitrogen, which,for example, is known to cause narcosis when used under great pressurein deep-sea diving.

It has been reported in U.S. Pat. No. 3,183,171 to Schreiner that argonand other inert gases can influence the growth rate of fungi and argonis known to improve the preservation of fish or seafood. U.S. Pat. No.4,946,326 to Schvester, JP 52105232, JP 80002271 and JP 77027699.However, the fundamental lack of understanding of these observationsclearly renders such results difficult, if not impossible, to interpret.Moreover, the meaning of such observations is further obscured by thefact that mixtures of many gases, including oxygen, were used in thesestudies. Further, some of these studies were conducted at hyperbaricpressures and at freezing temperatures. At such high pressures, it islikely that the observed results were caused by pressure damage tocellular components and to the enzymes themselves.

For example, from 1964 to 1966, Schreiner documented the physiologicaleffects of inert gases particularly as related to anesthetic effects andin studies relating to the development of suitable containmentatmospheres for deep-sea diving, submarines and spacecraft. The resultsof this study are summarized in three reports, each entitled: "TechnicalReport. The Physiological Effects of Argon, Helium and the Rare Gases,"prepared for the Office of Naval Research, Department of the Navy.Contract Nonr 4115(00), NR: 102-597. Three later summaries and abstractsof this study were published.

One abstract, "Inert Gas Interactions and Effects on EnzymaticallyActive Proteins, "Fed. Proc 26:650 (1967), . restates the observationthat the noble and other inert gases produce physiological effects atelevated partial pressures in intact animals (narcosis) and in microbialand mammalian cell systems (growth inhibition).

A second abstract, "A Possible Molecular Mechanism for the BiologicalActivity of Chemically Inert Gases," In: Intern. Congr. Physiol. Sci.,23rd, Tokyo, restates the observation that the inert gases exhibitbiological activity at various levels of cellular organization at highpressures.

Also, a summary of the general biological effects of the noble gases waspublished by Schreiner in which the principal results of his earlierresearch are restated. "General Biological Effects of the Helium-XenonSeries of Elements," Fed. Proc. 27:872-878 (1968).

However, in 1969, Behnke et al refuted the major conclusions ofSchreiner. Behnke et al concluded that the effects reported earlier bySchreiner are irreproducible and result solely from hydrostaticpressure, i.e., that no effects of noble gases upon enzymes aredemonstrable. "Enzyme-Catalyzed Reactions as Influenced by Inert Gasesat High Pressures." J. Food Sci. 34:370-375.

In essence, the studies of Schreiner were based upon the hypothesis thatchemically inert gases compete with oxygen molecules for cellular sitesand that oxygen displacement depends upon the ratio of oxygen to inertgas concentrations. This hypothesis was never demonstrated as thegreatest observed effects (only inhibitory effects were observed) wereobserved with nitrous oxide and found to be independent of oxygenpartial pressure. Moreover, the inhibition observed was only 1.9%inhibition per atmosphere of added nitrous oxide.

In order to refute the earlier work of Schreiner, Behnke et alindependently tested the effect of high hydrostatic pressures uponenzymes, and attempted to reproduce the results obtained by Schreiner.Behnke et al found that increasing gas pressure of nitrogen or argonbeyond that necessary to observe a slight inhibition of chymotrypsin,invertase and tyrosinase caused no further increase in inhibition, indirect contrast to the finding of Schreiner.

The findings of Behnke et al can be explained by simple initialhydrostatic inhibition, which is released upon stabilization ofpressure. Clearly, the findings cannot be explained by the chemical-O₂/inert gas interdependence as proposed by Schreiner. Behnke et alconcluded that high pressure inert gases inhibit tyrosinase in non-fluid(i.e., gelatin) systems by decreasing oxygen availability, rather thanby physically altering the enzyme. This conclusion is in direct contrastto the findings of Schreiner.

In addition to the refutation by Behnke et al, the results reported bySchreiner are difficult, if not impossible, to interpret for otherreasons as well.

First, all analyses were performed at very high pressure, and were notcontrolled for hydrostatic pressure effects.

Second, in many instances, no significant differences were observedbetween the various noble gases, nor between the noble gases andnitrogen.

Third, knowledge of enzyme mode of action and inhibition was very poorat the time of these studies, as were the purities of enzymes used. Itis impossible to be certain that confounding enzyme activities were notpresent or that measurements were made with a degree of resolutionsufficient to rank different gases as to effectiveness. Further, anyspecific mode of action could only be set forth as an untestablehypothesis.

Fourth, solubility differences between the various gases were notcontrolled, nor considered in the result.

Fifth, all tests were conducted using high pressures of inert gasessuperimposed upon 1 atmosphere of air, thus providing inadequate controlof oxygen tension.

Sixth, all gas effects reported are only inhibitions.

Seventh, not all of the procedures in the work have been fullydescribed, and may not have been experimentally controlled. Further,long delays after initiation of the enzyme reaction precluded followingthe entire course of reaction, with resultant loss of the highestreadable rates of change.

Eighth, the reported data ranges have high variability based upon asmall number of observations, thus precluding significance.

Ninth, the levels of inhibition observed are very small even at highpressures.

Tenth, studies reporting a dependence upon enzyme concentration do notreport significant usable figures.

Eleventh, all reports of inhibitory potential of inert gases at lowpressures, i.e., <2 atm., are postulated based upon extrapolated linesfrom high pressure measurements, not actual data.

Finally, it is worthy of reiterating that the results of Behnke et alclearly contradict those reported by Schreiner in several crucialrespects, mainly that high pressure effects are small and thathydrostatic effects, which were not controlled by Schreiner, are theprimary cause of the incorrect conclusions made in those studies.

Additionally, although it was reported by Sandhoff et al, FEBS Letters,vol. 62, no. 3 (March, 1976) that xenon, nitrous oxide and halothaneenhance the activity of particulate sialidase, these results arequestionable due to the highly impure enzymes used in this study and areprobably due to inhibitory oxidases in the particles.

To summarize the above patents and publications and to mention othersrelated thereto, the following is noted.

Behnke et al (1969), disclose that enzyme-catalyzed reactions areinfluenced by inert gases at high pressures. J. Food Sci. 34: 370-375.

Schreiner et al (1967), describe inert gas interactions and effects onenzymatically, active proteins. Abstract No. 2209. Fed. Proc. 26:650.

Schreiner, H. R. 1964, Technical Report, describes the physiologicaleffects of argon, helium and the rare gases. Contract Nonr 4115 (00),NR: 102-597. Office of Naval Research, Washington, D.C.

Schreiner, H. R. 1965, Technical Report, describes the physiologicaleffects of argon, helium and the rare gases. Contract Nonr 4115 (00),NR: 102-597. Office of Naval Research, Washington, D.C.

Schreiner, H. R. 1966, Technical Report, describes the physiologicaleffects of argon, helium and the rare gases. Contract Nonr 4115 (00),NR: 102-597. Office of Naval Research, Washington, D.C.

Importantly, in none of the above studies was the empirical conclusionreached that the treating gases had interacted with the enzyme activesites.

Nevertheless, at present, it is known that enzyme activities can beinhibited in several ways. For example, many enzymes can be inhibited byspecific poisons that may be structurally related to their normalsubstrates. Alternatively, many different reagents are known to bespecific inactivators of target enzymes. These reagents generally causechemical modification at the active site of the enzyme to induce loss ofcatalytic activity, active-site-directed irreversible inactivation oraffinity labeling. See Enzymatic Reaction Mechanisms by C. Walsh (W. H.Freeman and Co., 1979). Alternatively, certain multi-enzyme sequencesare known to be regulated by particular enzymes known as regulatory orallosteric enzymes. See Bioenergetics, by A. L. Leninger(Benjamin/Cummings Publishing Co., 1973).

However, it would be extremely advantageous if a much simpler approachcould be attained for regulating enzyme activities in a predictable andcontrollable manner. Moreover, it would be extremely advantageous if ameans could be found for selectively inhibiting or enhancing enzymeactivities in a predictable and controllable manner.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide amethod for regulating enzyme activities in a simple and straightforwardmanner.

It is also an object of the present invention to provide a method forregulating enzyme activities without using reagents which arestructurally designed to inactivate target enzymes.

It is also an object of the present invention to provide a method forregulating enzyme activities without using enzyme poisons which arestructurally related to normal enzyme substrates.

Furthermore, it is an object of the present invention to provide amethod of shifting optimal relative enzyme-substrate concentrations andto modify optimal reaction conditions in relation to physicalparameters.

The above objects and others which will become more apparent in view ofthe following disclosure are provided by a method for regulating enzymeactivities which entails contacting one or more enzymes with a gascomprising one or more noble gases.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the absorption spectrum of tyrosinase.

FIG. 2 illustrates the absorption spectrum of L-tyrosine.

FIG. 3 illustrates the absorption spectrum of tyrosinase and L-tyrosineblanked with L-tyrosine.

FIG. 4 illustrates an overlay of results of reactions run with varyingconcentrations of tyrosinase, showing direct linear first-ordertyrosinase concentration dependence.

FIG. 5 demonstrates the inhibition of tyrosinase by xenon at equal w/w.

FIG. 6 demonstrates a very large inhibition of tyrosinase by xenon at26° C.

FIG. 7 illustrates that at 15° C., argon slightly inhibits equilibriumof the tyrosinase-L-tyrosine reaction; xenon has a small but significantinhibitory effect and neon and krypton exhibit a large inhibitoryeffect.

FIG. 8 illustrates the inhibiting effects of xenon, krypton, neon andargon on the tyrosinase-L-tyrosine reaction at 20° C.

FIG. 9 illustrates that oxygen has no enhancing effect on thetyrosinase-L-tyrosine reaction at 20° C.

FIG. 10 illustrates the inhibitory effect of neon, argon, krypton andxenon on the tyrosinase-L-tyrosine reaction at 25° C.

FIG. 11 illustrates that oxygen has no enhancing effect on thetyrosinase-L-tyrosine reaction at 25° C.

FIG. 12 illustrates the inhibitory effect of neon, argon, krypton andxenon on the tyrosinase-L-tyrosine reaction at 30° C.

FIG. 13 illustrates that oxygen has no enhancing effect on thetyrosinase-L-tyrosine reaction at 30° C.

FIG. 14 illustrates a standard run in air at various temperatures, anddemonstrates that rate changes are directly attributable to oxygensolubility differences.

FIG. 15 illustrates the inhibitory effect of neon on thetyrosinase-L-tyrosine reaction which is positively temperaturedependent.

FIG. 16 illustrates the direct inverse (negative) relationship betweenthe ability of krypton to inhibit tyrosinase and temperature.

FIG. 17 illustrates the inhibition of tyrosinase-L-tyrosine equilibriumwith xenon, which interacts inversely with temperature.

FIG. 18 illustrates that at 20° C., oxygen does not enhance thetyrosinase-L-tyrosine reaction, whereas argon, xenon and neon eachdramatically inhibit the reaction. Krypton has a lesser inhibitoryeffect as does nitrogen.

FIG. 19 illustrates that at 25° C., argon and nitrogen inhibit thetyrosinase-L-tyrosine to a lesser extent than the noble gases, andoxygen enhances the reaction.

FIG. 20 illustrates that at 30° C., oxygen no longer enhances thetyrosinase-L-tyrosine reaction due to lessened solubility.

FIG. 21 illustrates the inhibition of the tyrosinase-L-tyrosine reactionby neon at various temperatures, and shows a transition between 20° C.and 25° C.

FIG. 22 illustrates the inhibition of the tyrosinase-L-tyrosine reactionby argon at various temperatures.

FIG. 23 illustrates the inhibition of the tyrosinase-L-tyrosine reactionby krypton at various temperatures.

FIG. 24 illustrates the inhibition of the tyrosinase-L-tyrosine reactionby xenon at various temperatures.

FIG. 25 illustrates the inhibition of the tyrosinase-L-tyrosine reactionpurely by a solubility mechanism involving the displacement of oxygenfrom solution.

FIG. 26 illustrates the inhibition of tyrosinase activity by nitrogen.

FIG. 27 illustrates the large difference in xenon activity between 20°and 25° C.

FIG. 28 illustrates the inhibition of glucose oxidase by krypton, xenon,argon, nitrogen and neon.

FIG. 29 illustrates the inhibition of α-glutamyltranspeptidase bykrypton, xenon, argon and a mixture of krypton and xenon.

FIG. 30 illustrates the inhibition of aspartate aminotransferase bykrypton, xenon, argon and a mixture of krypton and xenon.

FIG. 31 illustrates the enhancement of α-D-glucosidase by nitrogen, neonand oxygen.

FIG. 32 illustrates the enhancement of phenylalanine ammonia-lyase byneon, oxygen and nitrogen.

FIG. 33 illustrates the enhancement of citrate synthase by xenon andkrypton and the inhibition thereof by argon.

FIG. 34 illustrates the enhancement of phosphoglucose isomerase byxenon, krypton, argon and a mixture of krypton and xenon at 10° C.

FIG. 35 illustrates the enhancement of phosphoglucose isomerase by neonand nitrogen, and the inhibition thereof by oxygen at 25° C.

FIG. 36 illustrates the enhancement of S-acetyl CoA synthetase bykrypton and a mixture of krypton and xenon at 25° C.

FIG. 37 illustrates the inhibitory effect of air and nitrogen uponβ-glucosidase at 100 atm. pressure at 25° C.

FIG. 38 illustrates the inhibitory effect of air and nitrogen uponβ-glucosidase at 30 atm. pressure.

FIG. 39 illustrates the inhibitory effect of air, xenon and nitrogenupon tyrosinase at 30 atm. pressure.

FIG. 40 illustrates the inhibitory effect of air, xenon and nitrogenupon tyrosinase at 100 atm. pressure.

FIG. 41 illustrates that enzyme-substrate concentrations influence theresults of noble gas enhancement/inhibition.

FIG. 42 illustrates the differing effects of xenon and neon, inrespectively enhancing, then inhibiting lactate dehydrogenase at 10° C.,for example.

FIG. 43 illustrates that even at 60° C., noble gases exhibit enhancingor inhibitory effects on enzymes.

FIG. 44 illustrates the effect of xenon in enhancing β-glucosidase inimmobilized form.

FIG. 45 illustrates uv/vis absorbance power curves for β-glucosidaseunder air at five different substrate concentrations.

FIG. 46 illustrates uv/vis absorbance power curves for β-glucosidaseunder xenon at five different substrate concentrations.

FIG. 47 illustrates the first-order power curve regression rate lineartransformations for the β-glucosidase-air gassed reactions.

FIG. 48 illustrates the first-order power curve regression rate lineartransformations for the B-glucosidase-xenon gassed reactions.

FIGS. 49 and 50 illustrate the same first-order rate approximationregression linearizations for all gases studied in this run.

FIGS. 51 and 52 illustrate data from the first 160 seconds of a singletyrosinase experiment expressed as power curves for air, then xenongassing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the present invention, it has now been surprisinglydiscovered that enzyme activities can be regulated in a controlled andpredictable manner by contacting of one or more enzymes with a gascontaining one or more noble gases. Quite surprisingly, it has beendiscovered that noble gases have significant effects upon enzymes evenat low pressure, and over a wide range of temperature.

The present invention is, indeed, quite surprising, for several reasons.First, in accordance with the present invention, the regulation ofenzyme activities can be effected at low pressures. However, higherpressures may be used. Second, excellent results may also be obtainedwith mixtures of noble gases, including other gases such as nitrogen,oxygen carbon dioxide, carbon monoxide and nitrous oxide for example.Generally, any gas may be used in the gas mixtures in addition to thepresent noble gases. However, most typically such other gases includeoxygen, nitrogen and carbon dioxide.

As used herein the term "noble gas" means any gas from the group ofhelium, neon, argon, krypton, xenon or radon. However, it is generallypreferred that neon, argon, krypton or xenon be used simply becausehelium has a low solubility and high rate of departure from applicationsystems and radon is dangerously radioactive.

In accordance with the present invention, single, pure noble gas may beused, or mixtures of noble gases may be used. For example, it isadvantageous to use inexpensive production plant offstream gases havinga composition of about 90% Kr and 10% Xe, in volume % based on the totalgas volume. However, mixtures of one or more noble gases with othergases, such as nitrogen, sulfur hexafluoride, carbon oxygen or oxygenmay be used, for example.

In accordance with the present invention, it has been discovered thatthe effects of one or more noble gases upon enzyme activity is observedin aqueous or organic solutions, dispersions, suspensions or in othertypes of matrices, such as gels. Further, the enzymes regulated may bebound or unbound to supports. The noble gases, themselves, may be insolution, in the atmosphere or in a bound form.

The present invention is predicated upon the fundamental discovery thatenzymes representing all six enzyme classes, as classified by the JointCommission on Biochemical Nomenclature of the International Union ofBiochemistry and International Union of Pure and Applied Chemistry, arereproducibly enhanced or inhibited in their activity by contact even atlow pressures with pure noble gases or in mixtures thereof or even inmixtures with other gases.

In accordance with the present invention, it has been discovered thatthe gases and gas mixtures of the present invention can effect bothkinetic and thermodynamic control over enzymatic activity. That is, itis now possible to control both the rate and yield of an enzymaticreaction.

Although the solubility of the present gases and gas mixtures inreaction mixtures influences the measured effect of the gases and gasmixtures, the solubility does not wholly determine the effect. Theeffect is largely due to molecular effects such as polarizability,ionicity, Van der Waals forces and atomic radii. Generally, inaccordance with the present invention, increasing temperature will limitthe gas available due to decreasing solubility and decrease the effects.However, this decrease in effect offst by an increase in polarizabilitywith increasing temperature. Thus, at temperatures of about 30° C. andhigher, the increased polarizability of the gases and gas mixtures has amore pronounced influence as the effect of the gases and gas mixturesthan the solubility characteristics.

Generally, by increasing the molar concentration of the noble gas ornoble gas mixtures above standard temperature and pressure (STP), theobserved effect on the enzyme is increased. Further, the effects appearto be based upon the interaction of gas molecules with enzymes, which isindependent of, but can be ameliorated or potentiated by, the admixtureof other gases. Notably, mixtures of noble gases behave in the samemanner as pure noble gases, and mixtures of several gases are found tomimic, reverse or improve the effects observed with a single noble gas.

Additionally, in accordance with the present invention, it has beendiscovered that a particular noble gas or mixtures thereof may eitherinhibit or enhance enzymatic activity as a function of temperature.

Furthermore, in accordance with the present invention it has beendiscovered that, in general, under the appropriate conditions of pH,temperature, pressure, [E] and [S], all enzymes can be inhibitedspecifically by each of the noble gases of the present invention.

The present invention may be utilized to regulate enzyme activities inany application where enzymes are used. For example, the presentinvention may be used advantageously in the production of antibiotics,such as penicillin; in the production of ethanol and acetic acid; in themanufacture of diagnostic kits; in the manufacture of fermentationproducts, such as beer, wine and cheese; and in large scale enzymaticconversions generally.

As noted above, the present invention may be used advantageously inregulating the activities of enzymes from any of the six recognizedenzyme categories. The examples provided hereinbelow are illustrativeand are not intended to be limitative.

In particular, the present invention may be used advantageously inregulating oxidoreductases, which include, for example, dehydrogenases,oxidases, peroxidases, hydroxylases and oxygenases. Specific examples ofoxidoreductases are tyrosinase, glucose oxidase, acetoin dehydrogenase,taurine dehydrogenase, octopine dehydrogenase, azobenzene reductase,acetoindoxyl oxidase, hypotaurine dehydrogenase, pseudomonas cytochromeoxidase, 3-hydroxyanthranilate oxidase, chloride peroxidase, cytochromeC3 hydrogenase, meliotate 3-monooxygenase, CDP-4-keto-6-deoxydeglucosereductase and rubredoxin NaD⁺ reductase and chlorate reductase, forexample. However, any oxidoreductase enzyme may be used.

A second category of enzymes which can be regulated in accordance withthe present invention are the transferases. Specific examples oftransferases are carnosine N-methyl transferase, 3-oxoacyl acyl carrierprotein synthase, laminaribose phosphorylase, galactose 6-sulfurylase,diiodo tyrosine aminotransferase, sedoheptylokinase and psychosinesulfurotransferase, 8-glutamyl transpeptidase and aspartateaminotransferase, for example. However, any transferase may be used.

A third category of enzymes which can be regulated in accordance withthe present invention are hydrolases, which include esterases,phosphatases, glycosidases and peptidases, for example.

Specific examples of hydrolases are dihydrocoumarin hydrolase,β-D-glucosidase, α-glucosidase, ribosohomocysteinase, acylmuramylalaninecarboxypeptidase, ureidosuccinase, phloretin hydrolase and 2-haloaciddehalogenase, for example. However, any hydrolase may be used.

A fourth category of enzymes which can be regulated in accordance withthe present invention are lyases, including decarboxylases, aldolasesand dehydratases, for example. Specific examples of lyases arephenylalamine ammonia lyase, citrate synthetase, methyl glyoxylsynthase, ureidoglycolate lyase, alliin lyase, chorismate synthase andalkyl mercury lyase, for example. However, any lyase may be used.

A fifth category of enzymes which can be regulated in accordance withthe present invention are isomerases, including racemases, epimerases,cis-trans isomerases, intramolecular oxidoreductases and intramoleculartransferases, for example. Specific examples which may be mentioned areglucose phosphate isomerase, UDP arabinose 4-epimerase, maleylacetoacetate isomerase, chorismate mutase and muconate cycloisomerase,for example. However, any isomerase may be used.

A sixth category of enzymes which can be regulated in accordance withthe present invention are ligases, which include amino acid-RNA ligases,acid-thiol ligases, amide synthetases, peptide synthetases andcyclo-ligases, for example. Specific mention may be made of acetylcholine synthase, seryl-2-RNA synthetase, carnosine synthetase andmethyl crotonyl CoA carboxylase, for example. However, any ligase may beused.

Although the present invention generally provides a method forregulating enzyme activities, it also provides several additionalspecific methods.

First, the present invention also provides a method of enhancing enzymeactivities by contacting one or more enzymes with a gas containing oneor more noble gases or mixtures thereof.

Second, the present invention also provides a method of inhibitingenzyme activities by contacting one or more enzymes with a gascontaining one or more noble gases or mixtures thereof.

Third, the present invention provides a method of shifting the optimalpH and/or temperature of one or more enzymes by contacting one or moreenzymes with a gas containing one or more noble gases or mixturesthereof.

Fourth, the present invention provides a particular method forregulating oxidoreductase enzyme activities by contacting one or moreoxidoreductase enzymes with a gas containing one or more noble gases ormixtures thereof.

Fifth, the present invention also provides a method for the specificregulation of hydrolase enzymatic activity by contacting one or morehydrolase enzymes with a gas containing one or more noble gases ormixtures thereof.

Sixth, the present invention also provides a method for the specificregulatgion of lyase enzymatic activity by contacting one or more lyaseenzymes with a gas containing one or more noble gases or mixturesthereof.

Seventh, the present invention also provides a method for the specificregulation of isomerase enzymatic activity by contacting one or moreisomerase enzymes with a gas containing one or more noble gases ormixtures thereof.

Eighth, the present invention also provides a method for the specificregulation of ligase enzymatic activity by contacting one or more lyaseenzymes with a gas containing one or more noble gases or mixturesthereof.

Ninth, the present invention also provides a method for the specificregulation of transferase enzymatic activity by contacting one or moretransferase enzymes with a gas containing one or more noble gases ormixtures thereof.

Tenth, the present invention also provides a method for changing optimalrelative enzyme-substrate concentration by contacting one or moreenzymes with a gas containing one or more noble gases or mixturesthereof.

Eleventh, the present invention also provides a method for selectivelyregulating one enzyme in a mixture of two or more enzymes.

Importantly, the examples of enzymes listed above from each of the sixgeneral categories of enzymes are merely illustrative and are notintended to be limitative. In accordance with the present invention, anyenzyme may be regulated using the present gases and gas mixtures. Forexample, any of the enzymes described in Enzymes by M. Dixon and E. C.Webb, Third Edition (Academic Press) may be regulated in accordance withthe present invention.

Generally, as noted above, the gas containing one or more noble gasesmay be a single, pure noble gas or a mixture of noble gases. The gas mayalso be a mixture of one or more noble gases with other gases asmentioned above.

The enzymes may be in any form. For example, the enzyme regulated may bein aqueous, aqueous-based or organic solutions. The enzyme may also bein other matrices, such as a gel. Also, the enzyme may be in unbound orbound form, and even in bound form in cells, or in living cells, such asvegetables and other tissue.

In using the present invention to regulate bound enzymes, for example,the present invention may be used in numerous types of applications. Forexample, the bound enzymes may be in use in batch reactors,continuous-flow-stirred-tank reactors, column reactors, such as apacked-bed reactor, or even fluidized bed reactors.

Further, the use of bound enzymes in cells is advantageous where thecost of enzyme extraction and purification is prohibitive, or where theenzyme is unstable when removed from its native environment. Forexample, L-citrulline may be prepared using immobilized cells ofPseudomonas putida and urocanic acid may be prepared using immobilizedcells of Achromobacter liquidium.

Moreover, the present invention may also be used to regulate enzymeactivity in conjunction with enzyme electrodes, such as an electrodeused to measure glucose using glucose oxidase.

The present invention may be used advantageously whenever the regulationof enzyme activity in a controllable and predictable manner is desired.

In order to further describe the present invention, each of the sixbasic classes of enzymes will now be discussed in more detail.

I. Oxidoreductases

Generally, oxidoreductase enzymes are strongly inhibited by noble gases.However, the amount of inhibition varies from one noble gas to another,and from one noble gas mixture to another.

Xenon exhibits the largest effect on the rate of oxidoreductasereactions and depresses the final equilibrium of the reactions. Theother noble gases all inhibit the reaction rate and depress the finalequilibrium of the reaction to a lesser extent, depending both upontheir solubility and molecular properties. Krypton has a somewhat lessereffect than xenon, and argon is very active at low temperatures. Thus,in accordance with the present invention, different gas mixtures may beused to optimize oxidoreductase activity depending upon whether ambientor refrigerated temperatures are used.

By using one or more noble gases or mixtures thereof, variableoxidoreductase inhibitions obtained depending on the precise gas ormixture, substrate, temperature and gas pressure used.

II. Transferases

Generally, transferase enzymes are generally inhibited. For example,aminotransferases are inhibited and transpeptidases are inhibited by thenoble gases or mixtures thereof.

Generally, krypton exhibits the largest inhibitory or effect with somevariation depending upon the subclass of transferase which is subjectedthereto. Neon, by contrast, exhibits both the lowest inhibitory orenhancing effect depending upon the subclass of transferase used.

III. Hydrolases

Generally, all hydrolases are strongly enhanced by noble gases ormixtures thereof.

Notably, xenon exhibits the largest enhancing effect, whereas kryptonexhibits the least such effect.

However, if desired, hydrolases may also be inhibited.

IV. Lyases

In general, lyase enzymes are strongly or moderately enhanced by noblegases or mixtures thereof. However, some gases inhibit lyase enzymaticactivity under suboptimal conditions.

Xenon exhibits the largest enhancing effect, whereas argon exhibits theleast such effect.

V. Isomerases

In general, isomerase enzymes are either strongly or moderately enhancedby noble gases or mixtures thereof.

However, argon and mixtures containing the same can be induced toinhibit enzyme activity at higher temperatures.

VI. Ligases (Synthetases)

In general, ligase enzymes are strongly enhanced by noble gases ormixtures thereof.

In order to clarify the protocol used in measuring the effect of one ormore noble gases on enzymatic activity in accordance with the presentinvention, the following description of a typical and exemplaryexperimental protocol is provided:

General Protocol:

Solution preparation: Optimized w/v solutions are prepared by dilutingthe enzyme (units/ml) and the substrate (μg/ml) in appropriate buffer(optimized pH and molarity for enzymes). The solutions are used for gasexperiments at once to avoid loss of activity. Various enzyme andsubstrate concentrations and inhibitors may be employed. Physicalparameters are varied as required.

Spectrophotometric equipment: The experimental runs are performed with aPerkin-Elmer Lambda 6 UV/VIS spectrophotometer, temperature controlled,connected to an IBM PS/2 30 personal computer. The IBM is loaded withtwo software packages (PECSS or UVDM to record and view spectra,modified ENZFITTER and Grafit to do kinetic studies).

Full range spectra: The taking of full range spectra of enzyme andsubstrate species as well as completed reaction mixes allows thedetermination of a suitable wavelength to follow the enzymatic reaction(wavelength corresponding to the main absorbance peak), on a real-timebasis. Absorbent species are measured and blanked. Various chromogenicsubstrates may be used, and in certain circumstances, chromogenicreactions may be coupled to the enzyme reaction under study.

Dilution series: Dilution series are run to find the optimalenzyme/substrate ratio for proceeding with gas experiments. Reactionsare run at optimal conditions, then with super- and suboptimal substrateranges, then with various inhibitors.

Preparation of silicone sealed cuvets: 1-cm lightpath acrylic or quartzcuvets are stoppered with silicone rubber sealer. The silicone isallowed to cure for 48 hours in order to obtain gas-tight cuvets. Cuvetsare purged with air to remove any chemical gas contaminants as measuredby GC/MS, and tested for leaks.

Preparation of samples: Cuvets are filled with 2 ml of substratesolution by means of a gas-tight syringe. Gas-tight serum vials arefilled with enzyme and solvent. Sufficient gas is consecutively bubbledin the cuvets and serum vials, with a 1-hr wait between injections tomaximize equilibration of gas. All syringes and dead spaces are purgedbefore filling with the appropriate gas. The amount of gas used has beenmeasured sufficient to saturate the solution required.

Controls: All possible interfering parameters are controlled includingT, P, other gases, air leaks, materials, variation in gas and reagentquality, pH. Repetitions to significance are conducted.

Spectrophotometric time-drive, reaction rate, and kinetic analyses:cuvets and serum vials are saturated with gas 40 minutes before the run.A gas-filled syringe is used to retrieve 0.5 ml of enzyme solution toavoid air contact. The 0.5 ml syringe injections of enzyme are madesimultaneously to effect a common starting time to for the samples. 7gases (air, O₂, N₂, Ne, Ar, Kr, Xe) are run at various temperatures each(from 0° to 60° ). Changes in the rate or final equilibrium of thereaction versus ambient air are recorded. Comparison is also made withadded oxygen, and with deoxygenation. Some samples are also preparedunder pressure.

The Complete Experiment Protocol

In a complete experiment, an enzyme at optimal pH and buffering saltconcentration is reacted with 5 substrate concentrations in solutionwith noble gas at 1 atm. (saturated solution), at 10% and 50% ofsaturation, and at 1.5 and 2 atm. and at least one much higher pressure,and with supplemental oxygen equivalent to 10%, 20%, and 50% of totalgas at 1 and 2 atm. total pressure, at each temperature from 0°-65° C.in 5° increments, using N₂, O₂, Ar, Ne, Kr, Xe, Air, and occasionallyother gases, and using decile mixtures of the above gases, plus theenzyme is exposed to very high pressures in a hydrostatic control.Controls are also run after evacuation of solution by vacuum. Thereaction is monitored colorimetrically in a scanning spectrophotometerin real time, and the signals are treated mathematically to obtain rateand yield differences. Sample numbers are constant and sufficient toensure significance of results. All parameters are independentlycontrolled and measured, and more complex experiments are occasionallycarried out.

Data are obtained in the form of real-time product formation plots(standard rate curves), one for each sample cuvette, which are overlaidunder standard procedure to yield one overlay for each 6-12 cuvetteexperiment. Such an overlay is appended. The x-y data point tables whichmake up these curves plus all machine parameters are also produced.These data may be further transformed to calculate differences betweencurves, differences between yields, differences between rates, or otherlogical comparisons. These are calculated using several separatesoftware programs which utilize simple or complex ordinary mathematicalexpressions, linear and nonlinear regression curve fitting, log normaltransformations, enzymatic rate calculations (Michaelis-Menten,Eadie-Hofstee, Lineweaver-Burk), and time-dependent multivariateanalyses.

In order to more completely describe the present invention, referencewill now be made to certain examples which are provided solely forpurposes of illustration and are not intended to be limitative.

Class I. Oxidoreductases (EC1)

EXAMPLE 1

Tyrosinase; at 25° C. and optimal reaction conditions, simple saturationof solution with gas:

    ______________________________________                                        noble gas or mixture                                                                             effect                                                     ______________________________________                                        Xe                 -73% (Inhibition)                                          Kr                 -73%                                                       Ar                 -60%                                                       Ne                 -46.7%                                                     90:10 Xe:Kr mix    -50%                                                       Ar:Xe 99:1         -70%                                                       ______________________________________                                    

EXAMPLE 2

Glucose oxidase:

    ______________________________________                                        noble gas or mixture                                                                             effect                                                     ______________________________________                                        Xe                 -91.6% (Inhibition)                                        Kr                 -92.7%                                                     Ar                 -85.8%                                                     Ne                 -61.7%                                                     Maxima for class:                                                             Xe                 -95% (Inhibition)                                          Kr                 -91%                                                       Ar                 -91%                                                       Ne                 -85%                                                       ______________________________________                                    

Notably, the above results are dependent upon the temperature andsubstrate concentration.

Class II. Transferases (EC2)

EXAMPLE 3

Gamma-glutamyl transpeptidase:

    ______________________________________                                        noble gas or mixture                                                                              effect                                                    ______________________________________                                        Xe                  -7% (Inhibition)                                          Kr                  -8%                                                       Ar                  -5%                                                       Ne                  -3%                                                       ______________________________________                                    

EXAMPLE 4

Aspartate aminotransferase:

    ______________________________________                                        noble gas or mixture                                                                             effect                                                     ______________________________________                                        Xe                 -17% (Inhibition)                                          Kr                 -82%                                                       Ar                 -17%                                                       Ne                 -12%                                                       ______________________________________                                    

Class III. Hydrolases (EC3)

EXAMPLE 5

Beta-D-glucosidase:

    ______________________________________                                        noble gas or mixture                                                                             effect                                                     ______________________________________                                        Xe                 +40% (Enhancement)                                         Kr                 +14%                                                       Ar                 +16%                                                       90:10 Xe:Kr mix    +18%                                                       ______________________________________                                    

The above results are dependent upon temperature, substrateconcentration, and type of substrate. With the addition of differentcompeting substrates, enhancements of up to 200% were obtained usingxenon.

Class IV. Lyases (EC4)

EXAMPLE 6

Results are variable with temperature and [E/S]. For the citratesynthetase complex reaction:

    ______________________________________                                        35° C.      25° C.                                                                         10° C.                                      ______________________________________                                        Xe      +32              0     +18                                            Kr      +32             +6     +37                                            90:10     0            +16     -32                                            Ar      -15            -10     +25                                            Ne      -14             +9     +11                                            N.sub.2 -17            -25      -6                                            ______________________________________                                    

EXAMPLE 7

For phenylalanine ammonia lyase with optimized enzyme concentration:

    ______________________________________                                        Xe          +18        +3         +5                                          Kr          +7         +4         +4                                          90:10       +5         +2         +1                                          Ar          +6         +1         +3                                          Ne          -2         +6         -6                                          N.sub.2     +19        0          +6                                          ______________________________________                                    

EXAMPLE 8

For phenylalanine ammonia lyase with suboptimal enzyme concen.:

    ______________________________________                                        Xe          +14        +8         +11                                         Kr          +3         +18        +14                                         90:10       +5         +8         +6                                          Ar          -1         +1         +6.5                                        Ne          +15        0          +6                                          N.sub.2     0          0          +12                                         ______________________________________                                    

Class V. Isomerases (EC5)

EXAMPLE 9

Triosephosphate isomerase, 10° C.:

    ______________________________________                                        noble gas or mixture                                                                          effect                                                        ______________________________________                                        Xe              +24%    (Enhancement)                                         Kr              +12                                                           Ar              +8%     (but -37% inhibition                                                          at 25° C.                                      Ne              +4%                                                           90:10 Xe:Kr     +6.3%                                                         ______________________________________                                    

EXAMPLE 10

Phosphoglucose isomerase

    ______________________________________                                        noble gas or mixture                                                                           effect                                                       ______________________________________                                        Xe               +186% (-61% stressed)                                        Kr               +206.4%                                                      Ar               +232.5%                                                      Ne               +107% (-45% stressed)                                        ______________________________________                                    

Stressed refers to conditions of nonoptimal substrate concentration ortemperature.

Class VI. Ligases (Synthetases) (EC6)

These enzymes are enhanced but quite variable; extremely active sitespecific.

Maximum observed enhancement vs maximum observed inhibition (dependingupon temperature):

EXAMPLE 11

Acetyl S-CoA synthetase

In a coupled complex reaction sequence including hydrolytic enzymes:

    ______________________________________                                        Xe                 +18.3%/-25.0%                                              Kr                 +16.1%/-34.6%                                              Ar                 +67.7%/+34.6%                                              Ne                 +2.3%/-21.9%                                               90/10              +16.1%/-38.5%                                              N.sub.2            +31.2%/-39.5%                                              ______________________________________                                    

EXAMPLE 12

As an isolated reaction:

    ______________________________________                                        Xe               +15.4%/-39.5%                                                Kr               +5.0%/-52.6%                                                 Ar               +75.4%/-27.6%                                                90/10            +5.0%/-57.9%                                                 N.sub.2          +35.7%/-118.7%                                               ______________________________________                                    

In general, at higher temperatures, inhibition occurs. At lowtemperatures, enhancement occurs. Nitrogen usually has a much lessereffect than noble gases except at superoptimal temperatures. We areseeing noble gases enhancing this reaction towards optimal yields andrates under conditions which were otherwise suboptimal for the reaction.We are seeing mixed results under optimal conditions which depends uponthe gas used.

The present invention will now be further described by reference tofurther examples which are provided for purposes of illustration and arenot intended to be limitative.

Tyrosinase Catalyzed Reaction:

Tyrosinase (Monophenol, dihydroxyphenylalanine: oxygen oxidoreductase;EC 1.14.18.1) is a monophenol monooxygenase which catalyzes the reactionof ortho-diphenols to orthoquinones.

Tyrosinase is important in fruit browning and food product spoilage.

Experimental Protocol

1. Solution preparation: 10% w/v solutions are prepared by diluting theenzyme (units/ml) and the substrate (μg/ml) in Sodium Phosphate buffer(pH 6.85, optimized pH for enzymes). The solutions are stored inrefrigerator (0°-5° C.) and used for gas experiments within 2 or 3 daysto avoid loss of activity.

2. Spectrophotometric equipment: The experimental runs are performedwith a Perkin-Elmer Lambda 6 UV/VIS spectrophotometer connected to anIBM PS/2 30 personal computer. The IBM is loaded with two softwarepackages (PECSS to record and view spectra, ENZFITTER to do kineticstudies).

3. Full range spectra: The taking of full range spectra of E, S, and E+Sallows the determination of a suitable wavelength to follow theenzymatic reaction (wavelength corresponding to the main absorbancepeak).

4. Dilution series: Dilution series E vs S, and S vs E are run to findthe optimal [E]/[S] ratio for proceeding with gas experiments. Accordingto absorbance readings, the best of the two blanks (buffer +E or buffer+S) is chosen.

5. Preparation of silicone sealed cuvets: 1-cm lightpath acrylicdisposable cuvets are stoppered with clear silicone rubber sealer. Thesilicone is allowed to cure for 48 hrs in order to obtain gas tightcuvets.

6. Preparation of run samples: Acrylic cuvets are filled with 2 ml ofsubstrate solution by means of a gas tight syringe. Gastight serum vialsare filled with enzyme. 3×10 cc of gas are consecutively bubbled in thecuvets and serum vials, with a 1-hr wait between injections. Thisrepresents a 10× displacement of dead volume while maximizingequilibration of gas. All syringes and dead spaces are purged beforefilling with the appropriate gas. After the third 10 cc injection, thecuvets and serum vials are left overnight under two 10 cc syringesfilled with the appropriate gas in refrigerator at 0°-5° C.

7. Controls: All possible interfering parameters are controlled,including T, P, other gas, air leaks, materials, variation in gas andreagent quality, pH. Repetitions to significance are conducted.

8. Spectrophotometric runs: The cuvets and serum vials are filled with10 cc of gas 40 min before the run. A gas-filled syringe is used toretrieve 0.5 ml of enzyme solution to avoid air contact. The 0.5 mlsyringe injections of enzyme are made simultaneously to effect a commonstarting time t₀ for the samples. Seven gases (air, O₂, N₂, Ne, Ar, Kr,Xe) are run at five temperatures each (15° C., 20° C., 25° C., 30° C.,35° C.). Changes in the rate or final equilibrium of the reaction versusambient air are recorded.

2. REAGENTS:

Tyrosinase (Sigma Chemical Co., St. Louis, Mo.):

Catalog No. T-7755 (Lot 48F-9610)

Monophenol monooxygenase; Polyphenol oxidase; Catechol oxidase;Monophenol, dihydroxyphenylalanine: oxygen oxidoreductase; EC 1.14.18.1)

from Mushroom

25,000 units

12 mg solid

2,200 units/mg solid (Tyrosinase activity)

Tyrosinase unit definition: one unit will cause an increase in A₂₈₀ of0.001 per min at pH 6.5 at 25° C., using L-tyrosine as substrate.Reaction volume of 3 ml (1 cm light path)

Stored desiccated below 0° C.

L-Tyrosine (Sigma Chemical Co., St. Louis, Mo.):

Catalog No. T-3754 (Lot 48F-0833)

L-3-[4-Hydroxyphenyl]alanine

Free Base (pfs) Crystalline

Anhydrous Mol. Wt. 181.2

Stored at room temperature (25° C.)

Sodium Phosphate Monobasic (E K Industries, Addison, Ill.)

Catalog No. 8680

NaH₂ PO₄.H₂ O

Reagent Crystals

FW 137.99

Sodium Phosphate Dibasic (E K Industries, Addison, Ill.)

Catalog No. 8720

Na₂ HPO₄

Anhydrous

FW 141.96

Deionized water H₂ O (Barnstead NANOpure II)

3. SOLUTION PREPARATION:

Sodium Phosphate Buffer pH 6.85 (25° C.):

138 g NaH₂ PO₄.H₂ O

142 g Na₂ HPO₄

in 20 l D.I. H₂ O

Stored at room temperature (25° C.) in a plastic carboy

Tyrosinase solution (100 μg/ml; 208 units/ml; 2.08 units/μg):

10% w/v in Na Phosphate buffer

Mix several times by inversion to dissolve content

Stored in refrigerator [0°-5° C.] in 125 ml HDPE bottle wrapped inaluminum foil (to avoid light degradation)

L-Tyrosine solution (100 μg/ml):

10% w/v in Na Phosphate buffer

Magnetic stirring (25° C., 30 min)

Stored in refrigerator [0°-5° C.) in 250 ml amber glass bottle

4. GAS ATMOSPHERES:

Air (ambient)

Argon (Alphagaz, research grade)

Krypton (Alphagaz, research grade, minimum purity 99.995% [ppm])

Neon (Alphagaz, research grade, minimum purity 99.999% [ppm])

Nitrogen (Alphagaz, research grade, minimum purity 99.9995% [ppm]).

Oxygen (Alphagaz, research grade, minimum purity 99.997% (ppm]).

Xenon (Alphagaz, research grade, minimum purity 99.995% [ppm])

5. INSTRUMENTS AND MATERIALS:

5.1. Instruments:

Perkin-Elmer Lambda 6 UV/VIS Spectrophotometer (narrow-bandwidthspectrophotometer) equipped with automatic transport thermoelectricfive-cell holders (5×5 Sample and Reference Cell Holder, Model C005-0515)

Perkin-Elmer Lambda Accessory Interface (Model C691-0000)

Perkin-Elmer Digital Controller (Model C 570-0701)

Perkin-Elmer Temperature Programmer (Model C 570-0710)

IBM PS/2 30 personal computer

Epson EX800 printer

Software:

IBM DOS (Disk Operating System Version 3.30, Boca Raton, Fla.)

PECSS (Perkin-Elmer Computerized Spectroscopy Software, Norwalk, Conn.)

ENZFITTER (A Non-linear Regression Data Analysis Program,Elsevier-BIOSOFT, Cambridge, UK)

PIZAZZ PLUS (Print Enhancement Software, APTEC, Pepperell, Mass.)

Mettler AE100 Balance:

Weighing range: 0 . . . 109 g

Readability: 0.1 mg

Barnstead NANOpure II cartridge deionization system

Tokyo Rikakikai Co. Micro Tubing Pump MP-3 (for the Perkin-Elmer watercooled cells)

5.2. Materials:

100, 200 ml volumetric flasks

FISHERbrand Acrylic Cuvets (Standard Type/Methacrylate/UVGrade/Disposable): 1-cm lightpath, square cuvets capable of holding 3 mlof solution

100% Silicone Rubber Sealer (Clear)

3 ml Rubber Capped Serum Vials

1 ml in 1/100 ml Disposable Serological Pipets

1 cc in 1/100 cc Disposable Tuberculin Syringes

10 cc in 1/5 cc Disposable Syringes

2OG11/2%" Disposable Needles

6. DEVELOPMENT OF TECHNIQUE:

6.1. Initial observations:

Full range scans (900-190 nm) were run with tyrosinase, L-tyrosine, andthe final products of the enzymatic reaction.

6.1.1. Experimental set up:

PARAM: Absorbance

Slit 1 nm

Scan speed 1,500 nm/min

Response time 1 s

Autosave Yes

AZERO: Background correction (900-190 nm)

SCAN: Data interval 1.0 nm

Temperature: ambient (26° C.), temperature programmer off

6.1.2. Full range scans:

900-190 nm] scan of tyrosinase (FIG. 1):

Sample=2.5 ml tyrosinase (100 μg/ml)

Blank=2.5 ml Sodium Phosphate buffer

Filename: T775501.SP

(900-190 nm] scan of L-tyrosine (FIG. 2):

Sample=2.5 ml L-tyrosine (100 μg/ml)

Blank=2.5 ml Sodium Phosphate buffer

Filename: T375401.SP

900-190 nm] scan of the final products (FIGS. 3-4):

Sample=2 ml L-tyrosine (100 μg/ml) +0.5 ml tyrosinase (100 μg/ml) aftera time reaction of 20 minutes

Blank=2 ml L-tyrosine (100 μg/ml) +0.5 ml Na Phosphate buffer

Filename: TCEB0081.SP

6.1.3. Determination of the main absorbance peaks:

For this purpose, the graphics cursor (Home key) was used.

Tyrosinase: peak absorbance at 275 nm (protein)

L-Tyrosine: peak absorbance at 275 nm

The reaction final products: peak absorbance at 480 nm and 305 nm

6.1.4. Determination of a suitable wavelength to follow the reaction:

The overlay of the three full range spectra (FIG. 5) suggests optimalobservation of enzymatic oxidoreduction of L-tyrosine at either 480 or305 nm.

6.1.5. Determination of an appropriate [E]/[S] ratio:

    ______________________________________                                        T-3754        T-7755     Na Phos. Final                                       (100 μg/ml)                                                                              (100 μg/ml)                                                                           buffer   [E]                                         (ml)          (ml)       (ml)     (100 μg/ml)                              ______________________________________                                        Sample 5                                                                             2          0.1        0.4    20                                        Sample 4                                                                             2          0.2        0.3    40                                        Sample 3                                                                             2          0.3        0.2    60                                        Sample 2                                                                             2          0.4        0.1    80                                        Sample 1                                                                             2          0.5        0.0    100                                       ______________________________________                                    

Timedrives were run using the cell programmer (CPRG) command, whichrecords time drive data of up to 5 cells simultaneously.

Wavelength 480 nm: overlay (FIG. 6)

45 points, 60 s intervals 45 min run

    ______________________________________                                        TCEB0091.SP   [enz.] = 100 μg/ml                                                                              Cell 1                                     TCEB0092.SP   [enz.) =  80 μg/ml                                                                              Cell 2                                     TCEB0093.SP   [enz.] =  60 μg/ml                                                                              Cell 3                                     TCEB0094.SP   [enz.] =  40 μg/ml                                                                              Cell 4                                     ______________________________________                                    

Wavelength 305 nm: overlay (FIG. 7)

60 points, 60 s intervals 1 hr run

    ______________________________________                                        TCEB010I.SP   [enz.] = 100 μg/ml                                                                              Cell 1                                     TCEB0102.SP   [enz.] =  80 μg/ml                                                                              Cell 2                                     TCED0103.SP   [enz.] =  60 μg/ml                                                                              Cell 3                                     TCEB0104.SP   [enz.] =  40 μg/ml                                                                              Cell 4                                     TCEB0105.SP   [enz.] =  20 μg/ml                                                                              Cell 5                                     ______________________________________                                    

Conclusion:

The optimal conditions are [E]/[S] (100 μg/ml)/(100 μg/ml), the changesin absorbance being observed at 305 nm.

6.2. Preliminary experiments:

6.2.1. Preparation of samples and references:

Xenon saturated samples (see sampling procedure)

Air samples: acrylic cuvets filled with 2 ml of substrate T-3754 with a1 ml pipet, and capped with plastic cap. This procedure was laterchanged from the use of plastic caps to using silicone-sealed cuvets. Nosignificant differences were found. References (blanks): acrylic cuvetscapped with plastic cap.

B1: 2 ml T-3754 (100 μg/ml)+0.5 ml Na Phos. buffer

B2: 2 ml Na Phos. buffer+0.5 ml T-7755 (100 μg/ml)

6.2.2. Timedrives at 305 nm:

Blank B1:

AIR sample: filename=TCEB0114.SP

XENON sample: filename=TCEB0115.SP

Blank B2:

AIR sample: filename=TCEB0116.SP

XENON sample: filename=TCEB0117.SP

The L-tyrosine blank (B1) is found to depress absorbance readings, sothe tyrosinase blanked experiment (B2) is used in preference.

These 4 timedrives show an optimal inhibition curve for xenon. With thelater runs (6.3.7. and 7.2.) the L-tyrosine solution has decayed withtime, which induces a depletion in absorbance reading.

6.3. Development of technique:

6.3.1. Step 1: preparation of silicone-sealed cuvets

Acrylic disposable cuvets are stoppered with clear silicone rubbersealer. The silicone is allowed to dry for 24 hrs. After 24 hrs, we havegas-tight acrylic cuvets. These were tested for bubbling under water.

6.3.2. Step 2: substrate sampling procedure

Silicone-sealed acrylic cuvets are filled with 2 ml of substrate bymeans of a 1 cc syringe (in 1/100 cc).

To obtain accurate sampling, the syringe is tapped and vacated of air(which interferes with the substrate solution volume).

The filled cuvets are stored in refrigerator (0°-5° C.).

The blank B1 (2 ml T-3754+0.5 ml Na Phosphate buffer) is prepared in aplastic capped cuvet. This was changed later to the use ofsilicone-sealed cuvets.

6.3.3. Step 3: enzyme sampling procedure

Serum vials are filled with 2 ml of enzyme by means of a 1 ml pipet (in1/100 ml), capped with a rubber septum and crimp-sealed with an aluminumcap. Serum vials are gas-tight.

The filled serum vials are stored in refrigerator (0°-5° C.).

6.3.4. Step 4: gas saturation procedure (ARGON, KRYPTON, NEON, OXYGEN,XENON)

3×10 cc of gas are consecutively bubbled in the silicone-sealed cuvetsand serum vials (T-3754, T-7755), with a 1-hr wait between injections.This represents a 10× displacement of dead volume while maximizingequilibration of gas.

All syringes and deadspaces are purged before filling with theappropriate gas. After the third 10 cc injection, the silicone-sealedcuvets and serum vials are left overnight under two 10 cc syringesfilled with the appropriate gas in refrigerator at 0°-5° C.

6.3.5. Note:

The air samples (both enzyme and substrate) do not undergo any bubbling.The acrylic cuvet is stoppered with a regular vinyl cap (non gas-tight).This procedure was later changed to the use of silicone-sealed cuvettes.Multiple comparisons with sealed air-bubbled treatments show nodifference between the two methods.

6.3.6. Step 5: spectrophotometric runs

a. The silicone-sealed cuvets, serum vials and plastic capped cuvets areremoved from the refrigerator. This procedure is later changed (see7.1.5.)

b. The silicone-sealed cuvets and serum vials are filled with 10 cc ofgas and left at room temperature (26° C.) under two 10 cc syringes.

c. The cuvets are placed in the cell holder and allowed to equilibratein temperature with the cell holder for 10 min.

d. A 1 cc syringe is filled with the appropriate gas and used toretrieve 0.5 ml of enzyme solution from a serum vial, this to avoidintroduction of air in the vial while sampling the enzyme.

e. Run:

The sequential 0.5 ml syringe injections of enzyme into the cuvets areperformed as quickly as possible from cell 5 to cell 1 (delay x=2 sec).This procedure is later changed to concurrent injection.

6.3.7. Spectrophotometric runs: Timedrives at 305 nm

60 points, 60 s intervals 1 hr run

    ______________________________________                                        Run 1: T1 = 15° C. (T.sub.S = T.sub.R = 15.1° C.)               Filename        Gas      Cell no.                                             ______________________________________                                        B1T1G2.SP       Neon     Cell 2                                               B1T1G3.SP       Argon    Cell 3                                               B1T1G4.SP       Krypton  Cell 4                                               B1T1G5.SP       Xenon    Cell 5                                               ______________________________________                                        Run 2: T1 = 15° C. (T.sub.S = T.sub.R = 15.1° C.)               Filename        Gas      Cell no.                                             ______________________________________                                        B1T1G6.SP       Air      Cell 1                                               B1T1G7.SP       Oxygen   Cell 2                                               ______________________________________                                        Run 3: T2 = 20° C. (T.sub.S = T.sub.R = 20° C.)                 Filename        Gas      Cell no.                                             ______________________________________                                        B1T2G1.SP       Air      Cell 1                                               B1T2G2.SP       Neon     Cell 2                                               B1T2G3.SP       Argon    Cell 3                                               B1T2G4.SP       Krypton  Cell 4                                               B1T2G5.SP       Xenon    Cell 5                                               ______________________________________                                        Run 4: T2 = 20° C. (T.sub.S = T.sub.R = 20° C.)                 Filename        Gas      Cell no.                                             ______________________________________                                        B2T2G6.SP       Oxygen   Cell 1                                               ______________________________________                                        Run 5: T3 = 25° C. (T.sub.S = T.sub.R = 24.9°  C.)              Filename        Gas      Cell no.                                             ______________________________________                                        B1T3G1.SP       Air      Cell 1                                               B1T3G2.SP       Neon     Cell 2                                               B1T3G3.SP       Argon    Cell 3                                               B1T3G4.SP       Krypton  Cell 4                                               B1T3G5.SP       Xenon    Cell 5                                               ______________________________________                                        Run 6: T3 = 25° C. (T.sub.S = T.sub.R 24.9° C.)                 Filename        Gas      Cell no.                                             ______________________________________                                        B1T3G6.SP       Oxygen   Cell 1                                               ______________________________________                                        Run 7: T4 = 30° C. (T.sub.S = T.sub.R = 29.9° C.)               Filename        Gas      Cell no.                                             ______________________________________                                        B1T4G1.SP       Air      Cell 1                                               B1T4G2.SP       Neon     Cell 2                                               B1T4G3.SP       Argon    Cell 3                                               B1T4G4.SP       Krypton  Cell 4                                               B1T4G5.SP       Xenon    Cell 5                                               ______________________________________                                        Run 8: T4 = 30° C. (T.sub.S = T.sub.R = 29.9° C.)               Filename        Gas      Cell no.                                             ______________________________________                                        B1T4G6.SP       Oxygen   Cell 1                                               ______________________________________                                        Run 9: T5 = 35° C. (T.sub.S = T.sub.R = 34.9° C.)               Filename        Gas      Cell no.                                             ______________________________________                                        B1T5G1.SP       Air      Cell 1                                               B1T5G2.SP       Neon     Cell 2                                               B1T5G3.SP       Argon    Cell 3                                               B1T5G4.SP       Krypton  Cell 4                                               B1T5G5.SP       Xenon    Cell 5                                               ______________________________________                                        Run 10: T5 = 35° C. (T.sub.S = T.sub.R = 34.9° C.)              Filename        Gas      Cell no.                                             ______________________________________                                        B1T5G6.SP       Oxygen   Cell 1                                               ______________________________________                                    

7.3. Graphic results:

Timedrives overlay/Temperature--appended pages

Timedrives overlay/Gas--appended pages

7. FINAL PROCEDURE:

7.1. Final experimental protocol:

7.1.1 Step 1: preparation of silicone-sealed cuvets

Same as 6.3.1. but the silicone is allowed to cure for 48 hrs in orderto get rid of acetic acid vapors, which could interfere with the enzymeinhibition. This is confirmed by assay.

7.1.2. Step 2: substrate sampling procedure

Same as 6.3.2.

The blank B2 (2 ml Na Phosphate buffer+0.5 ml T-7755) is preparedaccording to the same procedure (in a silicone-sealed cuvet) but doesnot undergo the gas saturation step (7.1.4.).

Control checks show no absorbance by any of the gases within workingabsorbance range.

7.1.3. Step 3: enzyme sampling procedure

Same as 6.3.3.

7.1.4. Step 4: gas saturation procedure (AIR, ARGON, KRYPTON, NEON,NITROGEN, OXYGEN, XENON)

3×10 cc of gas are bubbled in the silicone-sealed cuvets and serum vials(T-3754, T-7755), with an interval of 20 min (at 0°-5° C.) between eachgas injection.

After the third 10 cc injection, the cuvets and serum via are leftovernight under two 10 cc syringes filled with the appropriate gas inrefrigerator at 0°-5° C.

7.1.5 Step 5: spectrophotometric runs

a. The silicone-sealed cuvets are removed from the refrigerator 40 minbefore the experimental run, filled with 10 cc of gas and left at roomtemperature (26° C.) under two 10 cc syringes.

b. The serum vials are removed from the refrigerator 25 min before theexperimental run, filled with 10 cc of gas and put back in therefrigerator under two 10 cc syringes.

c. 15 min before the run, the 10 cc syringes (and needles) are removedfrom the silicone-sealed cuvets. The cuvets are placed in the cellholder and allowed to equilibrate in temperature with the cell holderfor 10 min.

d. 5 min before the run, a 1 cc syringe is filled with the gas and usedto retrieve 0.5 ml of enzyme solution in the serum vials, this to avoidintroduction of air in the vial while sampling the enzyme.

e. Run:

The silicone-sealed cuvets are briefly removed from the cell holder andtapped to suppress gas bubbles that may form while the cuvets arewarming up (this is especially true at 30° and 35° C.), and replaced inthe cell holder.

The 0.5 ml syringe injections of enzyme are made simultaneously toeffect a common starting time t₀ for the samples.

7.2. Spectrophotometric runs: Timedrives at 305 nm

200 points, 18 s intervals 1 hr run

    ______________________________________                                        7.2.1. Run 1: T1 = 15° C. (T.sub.S = T.sub.R = 15. 1° C.)       Filename        Gas      Cell no.                                             ______________________________________                                        B2T1G1.SP       Air      Cell 1                                               B2T1G2.SP       Neon     Cell 2                                               B2T1G3.SP       Argon    Cell 3                                               B2T1G4.SP       Krypton  Cell 4                                               B2T1G5.SP       Xenon    Cell 5                                               ______________________________________                                        7.2.2. Run 2: T1 = 15° C. (T.sub.S = T.sub.R = 15.1° C.)        Filename        Gas      Cell no.                                             ______________________________________                                        B2T1G6.SP       Air      Cell 1                                               B2T1G7.SP       Oxygen   Cell 2                                               B2T1G8.SP       Nitrogen Cell 3                                               ______________________________________                                        7.2.3. Run 3: T2 = 20° C. (T.sub.S = T.sub.R = 19.9° C.)        Filename        Gas      Cell no.                                             ______________________________________                                        B2T2G1.SP       Air      Cell 1                                               B2T2G2.SP       Neon     Cell 2                                               B2T2G3.SP       Argon    Cell 3                                               B2T2G4.SP       Krypton  Cell 4                                               B2T2G5.SP       Xenon    Cell 5                                               ______________________________________                                        7.2.4. Run 4: T2 = 20° C. (T.sub.S = T.sub.R = 19.9° C.)        Filename        Gas      Cell no.                                             ______________________________________                                        B2T2G6.SP       Air      Cell 1                                               B2T2G7.SP       Oxygen   Cell 2                                               B2T2G8.SP       Nitrogen Cell 3                                               ______________________________________                                         7.2.5. Run 5: T3 = 25° C. (T.sub.S = T.sub.R = 24.9° C.)       Filename        Gas      Cell no.                                             ______________________________________                                        B2T3G1.SP       Air      Cell 1                                               B2T3G2.SP       Neon     Cell 2                                               B2T3G3.SP       Argon    Cell 3                                               B2T3G4.SP       Krypton  Cell 4                                               B2T3G5.SP       Xenon    Cell 5                                               ______________________________________                                        7.2.6. Run 6: T3 = 25° C. (T.sub.S = T.sub.R = 24.9° C.)        Filename        Gas      Cell no.                                             ______________________________________                                        B2T3G6.SP       Air      Cell 1                                               B2T3G7.SP       Oxygen   Cell 2                                               B2T3G8.SP       Nitrogen Cell 3                                               ______________________________________                                        7.2.7. Run 7: T4 = 30° C. (T.sub.S = T.sub.R = 29.9° C.)        Filename        Gas      Cell no.                                             ______________________________________                                        B2T4G1.SP       Air      Cell 1                                               B2T4G2.SP       Neon     Cell 2                                               B2T4G3.SP       Argon    Cell 3                                               B2T4G4.SP       Krypton  Cell 4                                               B2T4G5.SP       Xenon    Cell 5                                               ______________________________________                                        7.2.8. Run 8: T4 = 30° C. (T.sub.S = T.sub.R = 29.9° C.)        Filename        Gas      Cell no.                                             ______________________________________                                        B2T4G7.SP       Air      Cell 2                                               B2T4G8.SP       Oxygen   Cell 3                                               B2T4G9.SP       Nitrogen Cell 4                                               ______________________________________                                        7.2.9. Run 9: T5 = 35° C. (T.sub.S = T.sub.R = 34.9° C.)        Filename        Gas      Cell no.                                             ______________________________________                                        B2T5G1.SP       Air      Cell 1                                               B2T5G2.SP       Neon     Cell 2                                               B2T5G3.SP       Argon    Cell 3                                               B2T5G4.SP       Krypton  Cell 4                                               B2T5G5.SP       Xenon    Cell 5                                               ______________________________________                                        7.2.9. Run 10: T5 = 35° C. (T.sub.S = T.sub.R = 34.9° C.)       Filename        Gas      Cell no.                                             ______________________________________                                        B2T5G6.SP       Air      Cell 1                                               B2T5G7.SP       Oxygen   Cell 2                                               B2T5G8.SP       Nitrogen Cell 3                                               ______________________________________                                    

7.3. Graphic results:

Timedrives overlay/Temperature--appended pages

Timedrives overlay/Gas--appended pages

7.4. Enzyme kinetics: ENZFITTER

From the above results obtained from the tyrosinase-L-tyrosine reaction,the following conclusions may be drawn.

Xenon significantly inhibits the rate and depresses the finalequilibrium of the tyrosinase-L-tyrosine reaction. Moreover, the othernoble gases all inhibit the rate and depress the final equilibrium ofthe reaction to a lesser extent, depending both on their solubility andmolecular properties. Krypton generally has a similar but smaller effectas xenon, while argon is surprisingly active at low temperatures.

Further, the effects of oxygen depletion can be controlled through theuse of nitrogen. When compared with argon, nitrogen is found to lack thephysical ability for active site interaction. It appears that argon ismore active relative to nitrogen. This also appears to be true for otherenzyme classes.

As differences in solubility can explain only a portion of the observedinhibitions, active site interactions or induced protein conformationalchanges must occur.

Kinetic experiments are included hereinbelow.

High Pressure Experiments:

Experiments were conducted in pressure cells pressurized with additionaltest gas after solution was already saturated, at 2 atmospheres or at 3atmospheres in real-time, or after pressurizing in a 1-liter cylinderfor 1 hour or ˜24 hours at 30.6 atmospheres and at 100 atmospheres.

The following experimental procedures were used.

Protocol: Effects of High Pressure on Enzymes.

Theory: We will introduce enzymes to high pressures and determine theiractivity. High pressures should inhibit the activity of the enzymes.

Enzyme: Tyrosinase (SIGMA No. T-7755) (Monophenol monooxygenase;Polyphenol oxidase; Catechol oxidase; Monophenol,dihydroxyphenylalanine: oxygen oxidoreductase; EC 1.14.18.1)

From Mushroom

Tyrosinase Unit Definition:

One unit will cause an increase in A₂₈₀ of 0.001 per min at pH 6.5 at25° C. in 3 mL reaction mix containing L-tyrosine.

Tyrosinase activity: 3870 U/mg solid

7.1 mg solid 27,440 Units

Stored desiccated below 0° C.

Substrate: L-Tyrosine (SIGMA No. T-3754)

L-3-[4-Hydroxyphenyl]alanine

Free Base (pfs) Crystalline

Anhydrous Mol. Wt. 181.2

Stored at room temperature (25° C.)

Enzyme: β-D-Glucosidase (SIGMA No. G-4511)

(Emulsin; β-D-Glucoside glucohydrolase EC 3.2.1.21)

From Almonds

Unit Definition:

One unit will liberate 1.0 μmole of glucose from salicin per min at pH5.0 at 37° C.

Activity: 22 U/mg solid

12 mg solid 264 Units

Stored desiccated at 0°-5° C.

Lot# 49F-4021

Substrate: p-Nitrophenyl-β-D-Glucopyranoside (SIGMA No. N-7006)

Crystalline

Contains 2.4% solvent

Anhydrous Mol. Wt. 301.3

Stored desiccated below 0° C.

Lot# 129F-5057

Trial 1: Apr. 10, 1991-Apr. 11, 1991

Gasses: 1. Air

2. N₂

Pressures: 1. 30.6 atm (450 psi)

2. 100.0 atm (1470 psi)

Controls: Control A: enzyme not pressurized and not placed in the gascylinder.

Control B: enzyme not pressurized but placed in gas cylinder 1. Controlfor gas 1 (Air).

Control C: enzyme not pressurized but placed in gas cylinder 2. Controlfor gas 2 (N₂).

Solution Preparation: Apr. 10, 1991

Soln A: Sodium phosphate buffer pH 6.6 at 25° C.

1 L Deionized water

141.96×0.2×187.5×1/1000=5.3 g Na₂ HPO₄

119.96×0.2×312.5×1/1000=7.5 g NaH₂ PO₄

pH tested: 6.502

Soln B: Tyrosinase solution in Na Phos. buffer (228 u/ml)

14.2 mg T-7755 diluted to 240 mL Na Phos. buffer pH 6.6 at 25° C.

Soln C: 50 μg/ml L-Tyrosine solution in Na Phos. buffer

10 mg T-3754 diluted to 200 ml Na Phos. buffer pH 6.6 at 25° C.

Soln D: Sodium phosphate buffer pH 6.8 at 25° C.:

2 L Deionized water

2×141.96×0.2×245×1/1000=13.91 g Na₂ HPO₄

2×119.96×0.2×255×1/1000=12.20 g NaH₂ PO₄

pH tested: 6.719

Soln E: 100 μg/mL β-D-Glucopyranoside solution in Na Phos. buffer

25 mg N-7006 diluted to 250 ml Na Phos. buffer pH 6.8 at 25° C.

Soln F: β-D-Glucosidase solution in Na Phos. buffer pH 6.8 (25° C.)(2.18 Units/ml)

24 mg G-4511 diluted to 242 mL Na Phos. buffer pH 6.8 at 25° C.

Method: Tyrosinase: Apr. 11, 1991

Place a 100 ml aliquot of enzyme solution into each of 2 disposable gascylinders. Shake the enzyme in each cylinder for several minutes andthen remove a 5 ml sample for Control B and Control C. Remove cylindersto the dock, gassing with the appropriate gas; bring pressure slowly upto 30.6 atm. Let sit at the required pressure for 60 minutes. Slowlydepressurize to 2 psi before bringing into the lab.

Transfer approximately 10 ml of the enzyme from each cylinder whilekeeping it under gas into separate beakers and run a TDrive/CPRG on theenzyme/substrate mixture immediately.

Enzyme 1, Gas 1, Pressure 1, Repetition 1

Enzyme 1, Gas 2, Pressure 1, Repetition 1

Bring the cylinders back to the dock and repressurize to 100 atm withthe appropriate gas. Let sit at the required pressure for 60 minutes.Slowly depressurize to 2 psi before bringing into the lab.

Transfer approximately 10 ml of the enzyme from each cylinder whilekeeping it under gas into separate beakers and run a TDrive/CPRG on theenzyme/substrate mixture immediately.

Enzyme 1, Gas 1, Pressure 2, Repetition 1

Enzyme 1, Gas 2, Pressure 2, Repetition 1

β-Glucosidase:

Rinse the cylinders with copious quantities of D.I. H₂ O. Then rinse thecylinders with the second enzyme solution (glucosidase). Place a 25 mlaliquot of enzyme solution into each of 2 disposable gas cylinders.Shake the enzyme in each cylinder for several minutes and then remove a5 ml sample for Control B and Control C.

Remove cylinders to the dock, gassing with the appropriate gas; bringpressure slowly up to 30.6 atm. Let sit at the required pressure for 60minutes. Slowly depressurize to 2 psi before bringing into the lab.

Transfer approximately 10 ml of the enzyme from each cylinder whilekeeping it under gas into separate beakers and run a TDrive/CPRG on theenzyme/substrate mixture immediately.

Enzyme 2, Gas 1, Pressure 1, Repetition 1

Enzyme 2, Gas 2, Pressure 1, Repetition 1

Bring the cylinders back to the dock and repressurize to 100 atm withthe appropriate gas. Let sit at the required pressure for 60 minutes.Slowly depressurize to 2 psi before bringing into the lab.

Transfer approximately 10 ml of the enzyme from each cylinder whilekeeping it under gas into separate beakers and run a TDrive/CPRG on theenzyme/substrate mixture immediately.

Enzyme 2, Gas 1, Pressure 2, Repetition 1

Enzyme 2, Gas 2, Pressure 2, Repetition 1

Spectro Study: 25° C.

Cuvettes: 34 minimum

PARAM: slit 1

speed 1500

Asave Y

Aprint N

CPRG: Tyrosinase:

305 nm

18 Pts 20 min RUN

16s int

y_(min) =0.0

y_(max) =2.0

β-Glucosidase:

400 nm

40 Pts 10 min RUN

16s int

y_(min) =0.0

y_(max) =1.5

Blanks: Tyrosinase: 2 mL Soln A+0.5 mL Soln B

β-Glucosidase: 2 ml Soln E+0.5 mL Soln D

Sample: Tyrosinase: 2 ml Soln C+0.5 ml Soln B

β-Glucosidase: 2 ml Soln E+0.5 ml Soln F

Cell Transporter: Cell 1: Control A

Cell 2: Control B

Cell 3: Control C

Cell 4: Gas 1 (air)

Cell 5: Gas 2 (N₂)

Files: Tyrosinase:

X1P1G1C1...5.SP X1P1G1C1...5.SP were renamed X1P1E1C1...5.SP thru DOS.

X1P2E1C1...5.SP ...5.SP began with a higher abs so we tapped out the gasbubbles and did a full range scan of all 5 cells:

Full Range Scan 900-190 nm:

Files: X1SCAN₁...5. SP

--------------

10 FILES:

β-Glucosidase:

X2P1E2C1...5.SP

X2P2E2C1...5.SP

--------------

10 FILES:

Trial 2: Apr. 15, 1991

In this trial we will only do pressure tests of Tyrosinase.

Gasses: 1. Air

2. N₂

Pressures: 1. 30.6 atm (450 psi)

2. 100.0 atm (1470 psi)

Controls: Control A: enzyme not pressurized and not placed in the gascylinder.

Control B: enzyme not pressurized but placed in gas cylinder 1. Controlfor gas 1 (Air).

Control C: enzyme not pressurized but placed in gas cylinder 2. Controlfor gas 2 (N₂).

Solution preparation: Apr. 10, 1991

Soln A: Sodium phosphate buffer pH 6.6 at 25° C.

1 L Deionized water

141.96×0.2×187.5×1/1000=5.3 g Na₂ HPO₄

119.96×0.2×312.5×1/1000=7.5 g NaH₂ PO₄

pH tested: 6.502

Soln B: Tyrosinase solution in Na Phos. buffer (228 U/ml)

14.2 mg T-7755 diluted to 240 mL Na Phos. buffer pH 6.6 at 25° C.

Soln C: 50 μg/mL L-Tyrosine solution in Na Phos. buffer

10 mg T-3754 diluted to 200 ml Na Phos. buffer pH 6.6 at 25° C.

Method: Tyrosinase:

Place a 25 ml aliquot of enzyme solution into each of 2 disposable gascylinders. Shake the enzyme in each cylinder for several minutes andthen remove a 5 ml sample for Control B and Control C. Remove cylindersto the dock, gassing with the appropriate gas. Remove headspace/residualgas by pressurizing and depressurizing the gas cylinder several times.Bring pressure slowly up to 30.6 atm. Let sit at the required pressurefor 60 minutes. Slowly depressurize to 40 psi before bringing into thelab.

Transfer approximately 5 ml of the enzyme from each cylinder whilekeeping it under gas into separate beakers and run a TDrive/CPRG on theenzyme/substrate mixture immediately. Enzyme 1, Gas 1, Pressure 1,Repetition 2

Enzyme 1, Gas 2, Pressure 1, Repetition 2

Enzyme 1, Gas 2, Pressure 2, Repetition 2

Spectro Study: 25° C.

Cuvettes: 10 minimum

PARAM: slit 1

speed 1500

Asave Y

Aprint N

CPRG: Tyrosinase:

305 nm

80 Pts 20 min RUN

16s int

y_(min) =0.0

y_(max) =2.0

Blanks: Tyrosinase: 2 mL Soln A+0.5 mL Soln B

Sample: Tyrosinase: 2 ml Soln C+0.5 ml Soln B

Trial to see if Soln C is still usable:

TDrive: 305 nm, 80 pts, 16 s int.

S=2.0 ml C+0.5 ml B

R=2.0 ml A+0.5 ml D

Files: TYTRL1.SP

Cell Transporter:

Run 1: 100 atm

Cell 1: Control A

Cell 2: Control B

Cell 3: Control C

Cell 4: Gas 1 (air)

Cell 5: Gas 2 (N₂)

Run 2: 30 atm

Cell 1: Control A

Cell 2: Control B

Cell 3: Control C

Cell 4: Gas 1 (air)

Cell 5: Gas 2 (N₂)

Files: Tyrosinase:

X7P2E1C1...5.SP

X7P1E1C1...5.SP

--------------

10 FILES:

Trial 3: Apr. 24, 1991 (Soln prep and initial pressurization), Apr. 25,1991, Apr. 26, 1991

In this trial we will only do pressure tests of Tyrosinase.

Gases: 1. Air

2. N₂

3. Xe: 1 atm/N₂ to pressure

Pressures: 1. 30.6 atto (450 psi)

2. 100.0 atm (1470 psi)

Controls: Control A: enzyme not pressurized and not placed in the gascylinder.

Solution Preparation: Apr. 24, 1991

Soln A: Sodium phosphate buffer pH 6.8 at 25° C.

2 L Deionized water

2×141.96×0.2×245×1/1000=13.91 g Na₂ HPO₄

2×119.96×0.2×255×1/1000=12.20 g NaH₂ PO₄

pH tested: 6,740

Soln B: Tyrosinase solution in Na Phos. buffer (228 U/ml)

14.2 mg T-7755 diluted to 240 mL Na Phos. buffer pH 6.8 at 25° C.

Soln C: 50 μg/mL L-Tyrosine solution in Na Phos. buffer

10 mg T-3754 diluted to 200 ml Na Phos. buffer pH 6.8 at 25° C.

Method: Tyrosinase:

Apr. 24, 1991 Cylinder preparation: The cylinders (3) were put undervacuum then injected with 50 cc of D.I. H₂ O and put under pressure:Cylinder 1 with air

Cylinder 2 with N₂

Cylinder 3 with N₂

to 60 psi, shaken, turned upside down and the pressure released to blowthe liquid out of the cylinders. This process was repeated with 50 cc ofsodium phosphate buffer. The cylinders were pressurized as describedabove 3 times to remove all the liquid from the cylinders.

Enzyme injection: The cylinders were again placed under vacuum andinjected with 60 cc of Tyrosinase solution using the vacuum to suck theenzyme into the cylinder. The cylinders were pressurized as describedabove. The cylinder pressure was released and the cylindersrepressurized 10 times to remove O₂ from the cylinders.

Final Pressurization: Cylinders 1 (air) and 2 (N₂) were pressurized withthe corresponding gas to 30.6 atm. Cylinder 3 was pressurized to 1 atmwith Xe then pressurized to 30.6 atm with N₂ to conserve Xe.

Time Table: Cylinders were pressurized to 30 atm by 1:00 pm on 4/24/91.Due to the fact that on 4/25/91 the spectrophotometers were being usedat 5° C. for a different experiment the decision was made to sample thecylinders at the end of the day when the spectrophotometer was availableto be put at 25° C. Sampling took place 28 hours after pressurization. Aspectro/gas run was immediately preformed on these samples.

Apr. 25, 1991 Repressurization: Cylinders were repressurized at 6:00 pmon 4/25/91 to 100 atm. These cylinders will be sampled at 2:00 pm Apr.26, 1991 (20 hrs after pressurization).

Spectro Study: Apr. 25, 1991 25° C.

Cuvettes: 10 minimum

PARAM: slit 1

speed 1500

Asave Y

Aprint N

CPRG: Tyrosinase:

305 nm

80 Pts 20 min RUN

16s int

y_(min) =0.0

y_(max) =2.0

Blanks: Tyrosinase: 2 mL Soln A+0.5 mL Soln B

Sample: Tyrosinase: 2 ml Soln C+0.5 ml Soln B

Cell Transporter:

Run 1: 30 atm

Cell 1: Control A

Cell 2: Gas 1 (air)

Cell 3: Gas 2 (N₂)

Cell 4: Gas 3 (Xe:1 atm/N₂ :29 atm)

Files: Tyrosinase:

Y30G1...4.SP

--------------

4 FILES:

Spectro Study: Apr. 26, 1991 25° C.

Cuvettes: 10 minimum

PARAM: slit 1

speed 1500

Asave Y

Aprint N

CPRG: Tyrosinase:

305 nm

80 Pts 20 min RUN

16s int

y_(min) =0.0

y_(max) =2.0

Blanks: Tyrosinase: 2 mL Soln A+0.5 mL Soln B

Sample: Tyrosinase: 2 ml Soln C+0.5 ml Soln B

Cell Transporter:

Run 1: 100 atm

Cell 1: Control A

Cell 2: Gas 1 (air)

Cell 3: Gas 2 (N₂)

Cell 4: Gas 3 (Xe:1 atm/N₂ :29 atm)

Files: Tyrosinase:

Y100G1...4.SP

--------------

4 FILES:

Protocol: Effects of Pressure on Enzymes.

Enzyme: Tyrosinase (SIGMA No. T-7755)

(Monophenol monooxygenase; Polyphenol oxidase; Catechol oxidase;Monophenol, dihydroxyphenylalanine: oxygen oxidoreductase; EC 1.14.18.1)

From Mushroom

Tyrosinase Unit Definition:

One unit will cause an increase in A₂₈₀ of 0.001 per min at pH 6.5 at25° C. in 3 mL reaction mix containing L-tyrosine.

Tyrosinase activity: 3870 U/mg solid

7.1 mg solid 27,440 Units

Stored desiccated below 0° C.

Substrate: L-Tyrosine (SIGMA No. T-3754)

L-3-[4-Hydroxyphenyl]alanine

Free Base (pfs) Crystalline

Anhydrous Mol. Wt. 181.2

Stored at room temperature (25° C.)

Enzyme: β-D-Glucosidase (SIGMA No. G-4511)

(Emulsin; β-D-Glucoside glucohydrolase EC 3.2.1.21)

From Almonds

Unit Definition:

One unit will liberate 1.0 μmole of glucose from salicin per min at pH5.0 at 37° C.

Activity: 22 U/mg solid

12 mg solid 264 Units

Stored desiccated at 0°-5° C.

Substrate: p-Nitrophenyl-β-D-Glucopyranoside (SIGMA No. N-7006)

Crystalline

Contains 2.4% solvent

Anhydrous Mol. Wt. 301.3

Stored desiccated below 0° C.

Trial 1:

Gases: 1. Air

2. N₂

3. Ar

4. O₂

Pressures: 1. 2 atm (30 psi)

Solution Preparation: Apr. 29, 1991

prep: Apr. 26, 1991 Soln A: Sodium phosphate buffer pH 6.8 at 25° C.

2 L Deionized water

2×141.96×0.2×245×1/1000=13.91 g Na₂ HPO₄

2×119.96×0.2×255×1/1000=12.20 g NaH₂ PO₄ pH tested:

Soln B: Tyrosinase solution in Na Phos. buffer (228 U/ml)

14.2 mg T-7755 diluted to 240 mL Na Phos. buffer pH 6.8 at 25° C.

Soln C: 50 μg/mL L-Tyrosine solution in Na Phos. buffer

10 mg T-3754 diluted to 200 ml Na Phos. buffer pH 6.8 at 25° C.

Soln E: 100 μg/mL β-D-Glucopyranoside solution in Na Phos. buffer

25 mg N-7006 diluted to 250 ml Na Phos. buffer pH 6.8 at 25° C.

Soln F: β-D-Glucosidase solution in Na Phos. buffer pH 6.8 (25° C) (2.18Units/ml)

24 mg G-4511 diluted to 242 mL Na Phos. buffer pH 6.8 at 25° C.

Method: The cell transporters were removed from the spectrophotometersand the fixed cells were installed.

Acrylic cuvettes were prepared by first installing a blue silicone plug,needles and then sillconing the tops and sides of the cuvettes withgeneral all purpose silicone. These were left to cure for 48 hoursbefore use. When the silicone was cured the cuvettes were tappedvertically and then around the plug with strapping tape.

Sample prep: Apr. 29, 1991

Cuvettes were filled for the 2 atm experiments for both enzymes. Eachcuvette was gassed 10×10 cc with the appropriate gas and refrigeratedfor 15 minutes prior to running. Serum vials were filled with 5 cc ofthe corresponding enzyme and gassed with 10×10 cc of the appropriate gasprior to running. The spectrophotometers were set up such that acontinuous flow of each gas could be delivered to each spectro at alltimes. A 100 psi_(max) gauge was installed to read the cuvette pressureand 2 on/off valves were installed so that the reference cell could bepressurized during the second replicate. A ball valve was installedbetween the cylinder/house line and the gauge so that gas flow could becontrolled directly at the spectrophotometers. A check valve was placedin each line to ensure that a back pressure would not causecontamination of the house lines or the gas cylinders. The cuvettesretained the 2 needles during the entire run. One of the needles wasattached to the gas line while the second was used for enzymeintroduction and then plugged. Due to the bulky nature of the assemblyit was impossible to use the installed doors of the spectrophotometerstherefore they were removed. A 4-layer thick black felt cover wasprepared for each spectro to minimize the amount of light entering thesystem.

While the cuvette was equilibrating to temperature in thespectrophotometer both needles remained in the cuvette with 10 ccsyringes still attached. Prior to enzyme introduction one of thesyringes was removed while the gas line was attached to the needle. Asmall flow of gas run through the line while this was done to ensurethat there was no oxygen contamination. The needles remained above theliquid level. The second syringe was removed to allow constant flowthrough the cuvette. The enzyme was injected through the second needleusing a 1 cc syringe. The needle was then plugged, the cuvettepressurized and the run begun.

Apr. 29, 1991

2 atm

reference not pressurized

Tyrosinase: 1. Air nonpressurized reference or sample.

2. replicate 1 (reference cell not pressurized)

4 gases

Glucosidase: 1. Air nonpressurized reference or sample.

2. replicate 1 (reference cell not pressurized)

4 gases

Spectro Study: room temp

Cuvettes: 10

PARAM: slit 1

speed 1500

Asave Y

Aprint N

TDrive: Tyrosinase: New spectrophotometer (B)

305 nm

60 Pts 15 min RUN

16s int

y_(min) =0.0

y_(max) =1.6

β-Glucosidase: old spectrophotometer (A)

400 nm

60 Pts 15 min RUN

16s int

y_(min) =0.0

y_(max) =2.0

Blanks: Tyrosinase: 2 mL Soln A+0.5 mL Soln B

β-Glucosidase: 2 ml Soln E+0.5 mL Soln A

Sample: Tyrosinase: 2 ml Soln C+0.5 ml Soln B

β-Glucosidase: 2 ml Soln E+0.5 ml Soln F

Files:

Apr. 29, 1991

Tyrosinase:

Air reference (nonpressurized): 429TYTRL.SP

2 atm (unpressurized reference):

Y4E1P1G1...7.SP

Glucosidase:

Air reference (nonpressurized): 429GLUTR.SP

2 atm (unpressurized reference):

Y4E2P1G1...7.SP

Note: The temperature inside the fixed sample cell did not remainconstant which directly effects the results we obtain. We will removethe fixed cell holders on both spectrophotometers and replace them withthe cell transporters.

Trial 2: Apr. 30, 1991

Gases: 1. Air

2. N₂

3. Ar

4. O₂

Pressures: 1. 2 atm (30 psi)

Sample Preparation:

The solutions prepared on Apr. 29, 1991 will be reused.

Method:

The spectrophotometers were assembled for continuous gas flow asdescribed in Trial 1. Fixed cell holders were replaced with the celltransporters so that a constant temperature could be maintained usingthe Fisher Circulators and Digital Controllers. We continued to use theblack felt covers as they seem to provide suitable light protection.

A nonpressurized gas run using all four gases was done for each enzyme.Each cuvette was gassed with 10×10 cc of the corresponding gas andrefrigerated for 15 minutes. The 2 needles used for gassing the cuvetteswere removed when the cuvettes were placed into the spectrophotometer.Enzyme was introduced into the cuvettes using a 1 cc syringe with a20G11/2 needle attached. The needle was placed into the cuvette throughthe silicone plug but not immersed into the liquid. This was to ensurethat enzyme introduction into the cuvette was the same as for thepressurized gas run.

Serum vials were filled with 5 cc of the corresponding enzyme and gassedwith 10×10 cc of the appropriate gas prior to running.

Cuvettes:

Tyrosinase: The cuvettes with blue silicone, general all purposesilicone and strapping tape were used for this enzyme.

Glucosidase: The cuvettes with blue silicone only were used for thisenzyme.

All cuvettes were pressure tested to 32 psi before use.

Spectro Study:

Cuvettes: 26

PARAM: slit 1

speed 1500

Asave Y

Aprint N

TDrive: Tyrosinase: New spectrophotometer (B) 25° C.

305 nm

60 Pts 15 min RUN

16s int

y_(min) =0.0

y_(max) =1.6

β-Glucosidase: Old spectrophotometer (A) 35° C.

400 nm

60 Pts 15 min RUN

16s int

y_(min) 0.0

y_(max) =2.0

Blanks: Tyrosinase: 2 mL Soln A+0.5 mL Soln B

β-Glucosidase: 2 ml Soln E+0.5 mL Soln A

Sample: Tyrosinase: 2 ml Soln C+0.5 ml Soln B

β-Glucosidase: 2 ml Soln E+0.5 ml Soln F

Files:

Apr. 30, 1991

Tyrosinase:

Gas run (nonpressurized): Y6E1RSG1...4.SP

2 atm (reference nonpressurized):

Y6E1P1G1...4.SP

2 atm (reference pressurized):

Y7E1P1G1...4.SP

Glucosidase:

Gas run (nonpressurized): Y6E2RSG1 . . . 4.SP

2 atm (reference nonpressurized):

Y6E2P1G1 . . . 4.SP

2 atm (reference pressurized): Y7E2P1G1 . . . 4.SP

Note: We have decided to use the cuvettes with the blue silicone plugfor future pressure testing. The additional general all purpose siliconeand strapping tape seems to diminish the integrity of the gas tight sealthat the blue silicone has with the cuvette.

Trial 3: May 1, 1991

Gases: 1. Air

2. N₂

3. Ar

4. O₂

Pressures: 1. 3 atm (45 psi)

Sample Preparation:

The solutions prepared on Apr. 29, 1991 will be reused.

Method:

The same method as used in Trial 2 on Apr. 30, 1991 was used for thistrial.

Spectro Study:

Cuvettes: 31

PARAM: slit 1

speed 1500

Asave Y

Aprint N

TDrive: Tyrosinase: New spectrophotometer (B) 25° C.

305 nm

60 Pts 15 min RUN

16s int

y_(min) =0.0

y_(max) =1.6

β-Glucosidase: Old spectrophotometer (A) 35° C.

400 nm

60 Pts 15 min RUN

16s int

y_(min) =0.0

y_(max) =2.0

Blanks: Tyrosinase: 2 mL Soln A+0.5 mL Soln B

β-Glucosidase: 2 ml Soln E+0.5 mL Soln A

Sample: Tyrosinase: 2 ml Soln C+0.5 ml Soln B

β-Glucosidase: 2 ml Soln E+0.5 ml Soln F

Files:

May 1, 1991

Tyrosinase:

Gas run (nonpressurized): Y6E1SRG1 . . . 4.SP

Gas run (nonpressurized): Y7E1SRG1 . . . 4.SP

3 atm (reference nonpressurized):

Y6E1P2G1...4.SP

3 atm (reference pressurized): Y7E1P2G1 . . . 4.SP

Glucosidase:

Gas run (nonpressurized): Y6E2SRG1 . . . 4.SP

3 atm (reference nonpressurized):

Y6E2P2G1 . . . 4.SP (NEW BLANK USED)

3 atm (reference pressurized): Y7E2P2G1 . . . 4.SP

Trial 4: May 3, 1991

Gases: 5. Air

6. Ne

7. Kr

8. Xe

Pressures: 1.2 atm (30 psi)

Solution Preparation: May 2, 1991

prep: Apr. 26, 1991 Soln A: Sodium phosphate buffer pH 6.8 at 25° C.

2 L Deionized water

2×141.96×0.2×245×1/1000=13.91 g Na₂ HPO₄

2×119.96×0.2×255×1/1000=12.20 g NaH₂ PO₄

pH tested:

Soln B: Tyrosinase solution in Na Phos. buffer (228 U/ml)

7.1 mg T-7755 diluted to 120 mL Na Phos. buffer pH 6.8 at 25° C.

Soln C: 50 pg/mL L-Tyrosine solution in Na Phos. buffer

10 mg T-3754 diluted to 200 ml Na Phos. buffer pH 6.8 at 25° C.

Soln E: 100 μg/mL β-D-Glucopyranoside solution in Na Phos. buffer

12.5 mg N-7006 diluted to 125 ml Na Phos. buffer pH 6.8 at 25° C.

Soln F: β-D-Glucosidase solution in Na Phos. buffer pH 6.8 (25 ° C.)(2.18 Units/ml)

12 mg G-4511 diluted to 121 mL Na Phos. buffer pH 6.8 at 25° C.

Method:

The same method as used in Trial 2 and Trial 3 was used for this trialwith 2 exceptions. The needles were immersed into the liquid in thecuvette after the enzyme was injected into the cuvette and a quantity ofgeneral all purpose silicone was placed around the needles to preventgas from leaking out of the cuvette.

Spectro Study:

Cuvettes: 20

PARAM: slit 1

speed 1500

Asave Y

Aprint N

TDrive: Tyrosinase: New spectrophotometer (B) 25° C.

305 nm

40 Pts 10 min RUN

16s int

y_(min) =0.0

y_(max) =1.6

β-Glucosidase: Old spectrophotometer (A) 35° C.

400 nm

40 Pts 10 min RUN

16s int

y_(min) =0.0

y_(max) =2.0

Blanks: Tyrosinase: 2 mL Soln A+0.5 mL Soln B

β-Glucosidase: 2 ml Soln E+0.5 mL Soln A

Sample: Tyrosinase: 2 ml Soln C+0.5 ml Soln B

β-Glucosidase: 2 ml Soln E+0.5 ml Soln F

Files:

May 1, 1991

TDrive to check that the submerged needles do not pose a problem withabsorbance.

TDrive: 40 pts, 16 s int., 305 nm: TYRONEE1.SP

TDrive: 40 pts, 16 s int., 400 nm: GLUCNEE1.SP

Tyrosinase:

Gas run (nonpressurized): Y6E1SRG5 . . . 8.SP

2 atm (reference nonpressurized):

Y6E1P1G5 . . . 8.SP

Glucosidase:

Gas run (nonpressurized): Y6E2SRG5 . . . 8.SP

2 atm (reference nonpressurized):

Y6E2P1G5 . . . 8.SP

Note: If the needles entered the light path they were removed to abovethe liquid level. This was done by turning off the room lights and whilekeeping the felt cover in place working in the spectrophotometer.

Results

Results are given as % inhibition of gases relative to 1 atmosphere ofair/inhibition relative to 1 atmosphere after pressurization.

For tyrosinase:

    ______________________________________                                                      30.6 atm  100 atm                                               2 atm       3 atm   (24 hr) (1 hr)                                                                              (˜24 hr)                                                                       (1 hr)                               ______________________________________                                        Air  -7.0 & -15.4                                                                             -11.6   -37.0  -4.9 -65.8  -11.1                              Xe   -76.0/-86.2        -87.0       -85.7                                     Kr   -84.5/-93.1                                                              Ar   -76.9/-90.4                                                                              -55.8/                                                                        -72.1                                                         Ne   -69.0/-84.5                                                              N.sub.2                                                                            -71.2/-88.5                                                                              -72.1/  -78.8 -15.4 -84.7  -20.0                                              -82.6                                                         ______________________________________                                    

The change in relative effect is very great. For example, for Xenon itis 75%. This clearly evidences that pressure alone significantlyinhibits tyrosinase.

For betaglucosidase:

At 3 atmospheres pressure, the degree of enhancement observed waschanged as follows:

Air 0 (enhancement)>-12.5 (inhibition)

Xe +3.1>-15.7

Kr +2.0>-6.2

Ar +1.0>-13.2

Ne +1.0>-12.5

N₂ 0>-5.0

The above clearly indicates that reported inhibitions of hydrolases andother enzymes in prior art by noble gases are due to hydrostaticeffects.

Oxygen addition experiment:

Adding oxygen to tyrosinase lessened the effect of nitrogen completely.Adding oxygen lessened the effects of noble gases less well, clearlybecause the noble gases are affecting the enzyme through molecularproperties above and beyond simple competitive displacement of oxygenfrom solution. This evidence distinguishes noble gas effects from thoseof nitrogen. Also, addition of a small amount oxygen enhanced tyrosinaseactivity slightly (as expected for an oxygen-requiring reaction), butfurther addition of oxygen had no additional effect. Thus, reports ofstrict linear relationships between oxygen tension and enzyme activityare flawed, as they can describe only conditions of oxygen limitation.

Addition of oxygen to air gave a maximum of 6% increase in activity oftyrosinase.

Addition of oxygen up to a saturating amount to a xenon-saturatedsolution changed the effect of xenon from 85% inhibition to 50%inhibition.

Addition of oxygen as above to an argon-saturated solution changed theeffect of argon from an 82% to a 12% inhibition.

Addition of oxygen as above to a nitrogen-saturated solution completelyeliminated the effect of nitrogen from an 84% inhibition, yielding zeroinhibition.

There was no observed effect in adding oxygen to glucosidase reactionsas would be expected for an oxygen-independent reaction. The addition ofoxygen had no effect upon the action of any of the noble gases upon theenzyme, showing again that the effect of the noble gases upon the enzymeis dependent upon their molecular properties.

Gas Mixture Experiment

In addition to mixes of noble gases with nitrogen and oxygen, and ofmixes of Kr and Xe, serial mixes of Ar and either Xe or Kr were tested.

Results for tyrosinase expressed as inhibition vs. air control:

    ______________________________________                                        Mix = % Xe in AR                                                                          % inhibited                                                                              = % Kr in Ar                                                                              % inhibited                                ______________________________________                                        0           -75        0           -75                                        0.1         -72                                                               1.0         -73                                                               5.0         -83                                                               10.0        -81        10.0        -80                                        50.0        -78        50.0        -78                                        100.0       -86        100.0       -77                                        ______________________________________                                    

Similar results were obtained with betaglucosidase, wherein enhancementswere observed for all mixes, and these were of the same magnitude asthose for Xe, Kr or Ar depending upon the closeness of the mix to thepure gases.

Protocol: Gas Mixes

Theory: Enzyme activity will change with gas mix

Gas Mixes: 1. Ar/Xe

2. Ar/Kr

1. 0.1%

2. 1.0%

3. 5.0%

4. 10.0%

5. 50.0%

Enzyme: Tyrosinase (SIGMA No. T-7755) (Monophenol monooxygenase;Polyphenol oxidase; Catechol oxidase; Monophenol,dihydroxyphenylalanine: oxygen oxidoreductase; EC 1.14.18.1)

From Mushroom

Tyrosinase Unit Definition:

One unit will cause an increase in A₂₈₀ of 0-001 min at pH 6.5 at 25° C.in 3 mL reaction mix containing L-tyrosine.

Tyrosinase activity: 3870 U/mg solid

7.1 mg solid 27,440 Units

Stored dessicated below 0° C.

Lot# 8OH9615

Substrate: L-Tyrosine (SIGMA No. T-3754)

L-3-[4-Hydroxyphenyl]alanine

Free Base (pfs) Crystalline

Anhydrous Mol. Wt. 181.2

Stored at room temperature (25° C.)

Lot# 59F-0478

Enzyme: β-D-Glucosidase (SIGMA No. G-4511)

(Emulsin; β-D-Glucoside glucohydrolase EC 3.2.1.21)

From Almonds

Unit Definition:

One unit will liberate 1.0 μmole of glucose from salicin per min at pH5.0 at 37° C.

Activity: 22 U/mg solid

12 mg solid 264 Units

Stored dessicated at 0°-5° C.

Lot# 49F-4021

Substrate: p-Nitrophenyl-β-D-Glucopyranoside (SIGMA No. N-7006)

Crystalline

Contains 2.4% solvent

Anhydrous Mol. Wt. 301.3

Stored dessicated below 0° C.

Lot# 129F-5057

Solution Preparation:

prep: Apr. 15, 1991 Soln A: Sodium phosphate buffer pH 6.6 at 25 ° C.

1 L Deionized water

141.96×0.2×187.5×1/1000=5.3 g Na₂ HPO₄

119.96×0.2×312.5×1/1000=7.5 g NaH₂ PO₄

prep: Apr. 17, 1991 Soln B: Tyrosinase solution in Na Phos. buffer (228U/ml)

14.2 mg T-7755 diluted to 240 mL Na Phos. buffer pH 6.6 at 25° C.

prep: Apr. 17, 1991 Soln C: 50 μg/ml L-Tyrosine solution in Na Phos.buffer

10 mg T-3754 diluted to 200 ml Na Phos. buffer pH 6.6 at 25° C.

prep: Apr. 10, 1991 Soln D: Sodium phosphate buffer pH 6.8 at 25 ° C.:

2 L Deionized water

2×141.96×0.2×245×1/1000=13.91 g Na₂ HPO₄

2×119.96×0.2×255×1/1000=12.20 g NaH₂ PO₄

prep: Apr. 15, 1991 Soln E: 100 μg/ml β-D-Glucopyranoside solution in NaPhos. buffer

25 mg N-7006 diluted to 250 ml Na Phos. buffer pH 6.8 at 25° C.

prep: Apr. 17, 1991 Soln F: β-D-Glucosidase solution in Na Phos. bufferpH 6.8 (25° C.) (2.18 Units/ml)

24 mg G-4511 diluted to 242 mL Na Phos. buffer pH 6.8 at 25° C.

Method:

Apr. 17, 1991: Prep Solutions, purge cuvettes with air after making surethey are gas tight, fill cuvettes and refrigerate, prep enzyme serumvials and prep gas vials.

Apr. 18, 1991: Gas mix prep: 120 cc serum vials were used to mix thegassed in. These vials were purged using vacuum while 1 atm of argon wasmaintained in the vial. The vials were purged for 20 seconds in thismanner. The vials were under slight pressure which was released througha needle. This is considered 120 cc of Argon. The necessary volumes ofArgon and the gas to be mixed with (Xe or Kr) were then introduced intothe vials using a 30 cc syringe and needle.

    ______________________________________                                        %               Argon   Xe/Kr                                                 ______________________________________                                        0.1%            120 cc  0.2 cc                                                1.0%            118 cc  2.4 cc                                                5.0%            108 cc   12 cc                                                 10%             96 cc   24 cc                                                 50%             0 cc   120 cc                                                ______________________________________                                    

Trial 1:

We gassed the enzyme using 1 vial of gas mix using 8×10 cc of gas out ofthe vial. We gassed the cuvette/substrate using a second vial of gas mixusing 8×10 cc of gas out of the vial. Argon and Xenon were retrievedfrom the gas cylinders.

We filled the enzyme sampling syringes as follows:

    ______________________________________                                                enzyme        gas                                                     ______________________________________                                                Ar            Ar                                                              Xe            Xe                                                              0.1% Ar/Xe    Ar                                                              1.0% Ar/Xe    Ar                                                              5.0% Ar/Xe    Ar                                                      ______________________________________                                    

Cell Transporter:

Gas Mix: Ar/Xe, 1 repetition

Run 1: Cell 1: Ar

Cell 2: Xe

Cell 3: Ar/Xe 0.1%

Cell 4: Ar/Xe 1.0 %

Cell 5: Ar/Xe 5.0 %

(Replicate 1: R1)

PARAM: slit 1

speed 1500

Asave Y

Aprint N

CPRG: Tyrosinase: 25° C.

305 nm

80 Pts 20 min RUN

16s int

y_(min) =0.0

y_(max) =2.0

B-Glucosidase: 35° C.

400 nm

60 Pts 15 min RUN

16s int

y_(min) =0.0

y_(max) =1.5

Blanks: Tyrosinase: 2 mL Soln A+0.5 mL Soln B

β-Glucosidase: 2 ml Soln E+0.5 mL Soln D

Sample: Tyrosinase: 2 ml Soln C+0.5 ml Soln B

β-Glucosidase: 2 ml Soln E+0.5 ml Soln F

Files:

Tyrosinase:

X9R1G1M1 . . . 5.SP

Glucosidase:

XOR1G1M1 . . . 5.SP

Results of Trial 1:

We found that we has air contamination in the Tyrosinase run and assumedthat the same was true for the glucosidase run. We determined that wewould be unable to retrieve 8×10 cc of gas mix from 1 vial. Therefore wedetermined that we would prepare 2 vials of gas mix per cuvette forgassing and 2 vials of gas mix per enzyme which would enable us to do10×10 cc per cuvette/vial.

Trial 2:

We gassed the second run using 2 vials of gas mix per cuvette and 2vials of gas mix per enzyme. We then proceeded to do the last 2 gasmixes (10% and 50%).

Gas Mix: Ar/Xe, 1 repetition

Cell Transporter:

Run 2: Cell 1: Ar

Cell 2: Xe

Cell 3: Ar/Xe 10.0%

Cell 4: Ar/Xe 50.0%

Cell 5: Air

(Replicate 1: R1)

PARAM: slit 1

speed 1500

Asave Y

Aprint N

CPRG: Tyrosinase: 25° C.

305 nm

80 Pts 20 min RUN

16s int

y_(min) =0.0

y_(max) =2.0

β-Glucosidase: 35° C.

400 nm

60 Pts 15 min RUN

16s int

y_(min) =0.0

y_(max) =1.5

Blanks: Tyrosinase: 2 mL Soln A+0.5 mL Soln B

β-Glucosidase: 2 ml Soln E+0.5 mL Soln D

Sample: Tyrosinase: 2 ml Soln C+0.5 ml Soln B

β-Glucosidase: 2 ml Soln E+0.5 ml Soln F

Files:

Tyrosinase:

X9R1G1M6 . . . 0.SP

Glucosidase:

XOR1G1M6 . . . 0.SP

Results of Trial 2:

Tyrosinase gave a separation such that we would expect therefore we willassume that our new method of gassing is appropriate and will continueto gas in this fashion. Glucosidase does not show a large separationtherefore due to time constraints we will focus on Tyrosinasespecifically the 10% and 50% gas mixtures.

Run 3: Cell 1: Ar

Cell 2: Xe

Cell 3: Ar/Xe 10.0%

Cell 4: Ar/Xe 50.0%

Cell 5: Air (Replicate 2: R2 )

Files:

Tyrosinase:

X9R2G1M6 . . . 0.SP

We prepared the Ar/Kr mixes as described above and did 2 replicates ofthe 10% and 50% mixes.

Run 4/5: Cell 1: Ar

Cell 2: Kr

Cell 3: Ar/Kr 10.0%

Cell 4: Ar/Kr 50.0%

Cell 5: Air

(Replicate 1, 2: R1, R2)

Files:

Tyrosinase:

X9R1G2M6 . . . 0.SP

X9R2G2M6 . . . 0.SP

Results:

Results with Ar/Xe look much better than the results we got with Ar/Kr.We will continue to do replicates of both mixes using 10% and 50%. Timepermitting we will so replicates of 0.1%, 1% and 5% of both gas mixeswith Tyrosinase only.

Apr. 19, 1991:

Tyrosinase 2 replicates Ar/Xe on one spectrophotometer and Ar/Kr on theother spectro.

New Spectro:

Run 1: Cell 1: Ar

Cell 2: Xe

Cell 3: Ar/Xe 10.0%

Cell 4: Ar/Xe 50.0%

Cell 5: Air

(Replicate 3: R3)

Run 2: Cell 1: Ar

Cell 2: Xe

Cell 3: Ar/Xe 10.0%

Cell 4: Ar/Xe 50.0%

Cell 5: Air

(Replicate 4: R4)

Old Spectra:

Run 1: Cell 1: Ar

Cell 2: Kr

Cell 3: Ar/Kr 10.0%

Cell 4: Ar/Kr 50.0%

Cell 5: Air

(Replicate 3: R3)

Run 2: Cell 1: Ar

Cell 2: Kr

Cell 3: Ar/Kr 10.0%

Cell 4: Ar/Kr 50.0%

Cell 5: Air

(Replicate 4: R4)

PARAM: slit 1

speed 1500

Asave Y

Aprint N

CPRG: Tyrosinase: 25° C.

305 nm

80 Pts 20 min RUN

16s int

y_(min) =0.0

y_(max) =2.0

Blanks: Tyrosinase: 2 mL Soln A+0.5 mL Soln B

Sample: Tyrosinase: 2 ml Soln C+0.5 ml Soln B

Files: Ar/Xe:

X9R3G1M6 . . . 0.SP

X9R4G1M6 . . . 0.SP

--------------

10 FILES

Ar/Kr:

X9R3G2M6 . . . 0. SP

X9R4G2M6 . . . 0. SP

--------------

10 FILES

Time permitting:

We were only able to run the following:

New Spectro:

Run 3: Cell 1: Ar

Cell 2: Xe

Cell 3: Ar/Xe 0.1%

Cell 4: Ar/Xe 1.0%

Cell 5: Ar/Xe 5.0%

(Replicate 2: R2)

Run 4: Cell 1: Ar

Cell 2: Xe

Cell 3: Ar/Xe 0.1%

Cell 4: Ar/Xe 1.0%

Cell 5: Ar/Xe 5.0%

(Replicate 3: R3)

Files: Ar/Xe:

X9R2G1M1 . . . 5.SP

X9R3G1M1 . . . 5.SP

--------------

10 FILES

Thus, the present invention generally provides a method of regulatingenzymatic activity by contacting one or more enzymes with a gascontaining one or more noble gases or mixtures thereof.

In accordance with the present invention, the enzyme regulated may be asingle, isolated enzyme or one or more enzymes which comprise a mixture.For example, in accordance with the present invention, a mixture ofenzymes may be regulated by selectively inhibiting the activities of oneor more enzymes and selectively enhancing the activities of one or moreenzymes.

Furthermore, enzymatic activity may be regulated in accordance with thepresent invention over a temperature range of from the boiling point ofliquid nitrogen (about -200° C.) to about 120° C.

In accordance with the present invention, any enzyme can be regulatedusing the present noble gases. However, by selecting the appropriateconditions of pH, temperature, pressure, [E] and [S], all enzymes can beinhibited specifically by all of the noble gases of the presentinvention. Furthermore, it is within the skill of the artisan to utilizethe present disclosure and guidelines set forth hereinabove to determinethe optimal levels of pH, temperature, pressure, [E] and [S] for anyparticular enzyme system or mixed enzyme system of interest.

The figures of the present specification will now be discussed in moredetail.

FIG. 1 illustrates the absorption spectrum of 2.5 ml tyrosinase (100μg/ml) vs. 2.5 ml sodium phosphase buffer at pH 6.85.

FIG. 2 illustrates the absorption spectrum of 2.5 ml L-tyrosine (100μg/ml) vs. 2.5 ml sodium phosphase buffer at pH 6.85.

FIG. 3 illustrates the absorption spectrum of tyrosinase and L-tyrosineblanked with L-tyrosine at the concentrations and pH indicated.

FIG. 4 illustrates an overlay of results of reactions run with varyingconcentrations of tyrosinase (40, 60, 80 and 100 μg/ml), showing directlinear first-order tyrosinase concentration dependence.

FIG. 5 illustrates the inhibition of tyrosinase by xenon at equal (w/w),using the concentrations and pH indicated.

FIG. 6 illustrates a very large inhibition of tyrosinase by xenon at 26°C. and is estimated to be approximately (area air run curve=11217μ,xenon=3037μ, total=14254μ, % total area air=78.69%, xenon=21.31, xenontotal area=27.08% of air area, inhibition of air rate by xenon=72.92%.This rate of inhibition is extremely large relative to otherconventional enzyme inhibitors.

FIG. 7 illustrates that 15° C., argon slightly inhibits equilibrium ofthe tyrosinase-L-tyrosine reaction, xenon exhibits a small, butsignificant inhibitory effect, and neon and krypton exhibit strongeffects. Oxygen and air exhibit approximately the same effect.

FIG. 8 illustrates that at 20° C., xenon inhibits thetyrosinase-L-tyrosine reaction quite strongly, whereas the other gasesneon, krypton and argon are all effective inhibitors.

FIG. 9 illustrates that oxygen has only a moderate inhibitory effect onthe tyrosinase-L-tyrosine reaction.

FIG. 10 illustrates the strong inhibition at 20° C. of thetyrosinase-L-tyrosine reaction by argon, with krypton being almost ofequal effect. However, the other gases indicated are also effectiveinhibitors.

FIG. 11 illustrates that oxygen has only a slight inhibitory effect onthe tyrosinase-L-tyrosine reaction of 25° C.

FIG. 12 illustrates the inhibitory effect of neon, argon, krypton andxenon on tyrosinase activity at 30° C.

FIG. 13 ilustrates the inhibitory effect of oxygen ontyrosinase-L-tyrosine activity at 30° C.

FIG. 14 illustrates a standard tyrosinase-L-tyrosine reaction run in airshowing rate changes directly attributable to oxygen solubilitydifferences. The curves obtained with oxygen instead of air areidentical.

FIG. 15 illustrates an inhibitory effect with neon which is temperaturedependent.

FIG. 16 illustrates a direct inverse (negative) relationship between theability of krypton to inhibit tyrosinase and temperature.

FIG. 17 illustrates that xenon inhibits the equilibrium of thetyrosinase-L-tyrosine reaction better than other gases, byt depressesthe rate only as well as krypton and argon for this reaction. Further,the variability in curve shape is high, which strangely suggests adirect active site interaction with tyrosinate. Xenon interactsinversely with temperature and shares a dynamic transition of effectbetween 20° C. and 25° C.

FIG. 18 illustrates that at 20° C. argon, xenon and neon alldramatically inhibit tyrosinase activity, whereas krypton has a lessereffect. Nitrogen also inhibits the reaction fairly well, however, oxygenexhibits little effect.

FIG. 19 illustrates that at 25° C., argon and nitrogen inhibit at alesser level than the other noble gases, whereas oxygen enhances thereaction. The small difference in curve shape between the krypton-xenonand neon-argon curve pairs is highly significant due to the likelyrelative effects of Van der Waals exclusion and oxygen dilution.

FIG. 20 illustrates that at 30° C., oxygen no longer enhances tyrosinaseactivity due to lessened solubility. Xenon inhibits the reaction muchbetter than other gases, although all are effective.

FIG. 21 illustrates the inhibition of tyrosinase activity by neon, withan activity transition occuring between 20° C. and 25° C.

FIG. 22 illustrates the inhibition of tyrosinase activity by argon,showing better inhibition by argon at 20° C. than neon, but lessinhibition at 25° C. than neon. These differences are considered to bedirectly attributable to solubility/oxygen diffusabilities.

FIG. 23 illustrates the inhibition of tyrosinase activity by kryptonwith an activity transition occuring between 20° C. and 25° C. Thisprovides strong evidence for a direct interaction between the gas andthe enzyme active site,

FIG. 24 illustrates the existence of at least two activity transitionsfor xenon in the inhibition of tyrosinase activity. A first activitytransition is between 25° C. and 30° C., and a second is between 30° C.and 35° C. A third activity transition may exist between 20° C. and 25°C. These trnasitions provide strong evidence for a direct interactionbetween the gas and the enzyme active site.

FIG. 25 illustrates the inhibition of tyrosinase purely by a solubilitymechanism involving the displacement of oxygen from solution. Air showsthe expected dissolution--driven rate pattern, while oxygen saturates at30° C.

FIG. 26 illustrates the inhibition of tyrosinase activity by nitrogen.Nitrogen can only inhibit enzymes by a solubility mechanism involvingthe displacement of oxygen from solution, but is effective in inhibitingtyrosinase activity. A transitional maxima is observed after 20° C. Thedifference between the nitrogen curves and noble gas curves representspotential active site inhibition. In most cases, these differences aresignificant for each gas at at least one temperature.

FIG. 27 illustrates the large difference in xenon activity between 20°C. and 25° C. This corresponds with an enzyme active site opticaltemperature.

FIG. 28 illustrates the inhibition of glucose oxidase by krypton, xenon,argon, nitrogen and neon.

FIG. 29 illustrates the inhibition of α-glutamyltranspeptidase bykrypton, xenon, argon and a mixture of krypton and xenon.

FIG. 30 illustrates the inhibition of aspartate aminotransferase bykrypton, xenon, argon and a mixture of krypton and xenon.

FIG. 31 illustrates the enhancement of α-D-glucosidades by SF₆, argon,nitrogen, neon and oxygen.

FIG. 32 illustrates the enhancement of phenylalanine ammonia-lyase byneon, oxygen and nitrogen.

FIG. 33 illustrates the enhancement of citrate synthase by xenon andkrypton and the inhibition thereof by argon.

FIG. 34 illustrates the enhancement of phosphoglucose isomerase byxenon, krypton, argon and a mixture of krypton and xenon at 10° C.

FIG. 35 illustrates the enhancement of phosphoglucose isomerase by neonand nitrogen, and the inhibition thereof by oxygen at 25° C.

FIG. 36 illustrates the enhancement of S-acetyl CoA synthetase bykrypton and a mixture of krypton and xenon at 25° C.

FIG. 37 illustrates the inhibitory effect of air and nitrogen uponβ-glucosidase at 100 atm. pressure. This effect is simply due to enzymedamage due to high pressure.

FIG. 38 illustrates the inhibitory effect of air and nitrogen uponβ-glucosidase at 30 atm. pressure. This effect is similarly due enzymedamage from high pressure.

FIG. 39 illustrates the inhibitory effect of air, xenon and nitrogen ontyrosinase activity at 30 atm. pressure. The ffect is due to enzymedamage from high pressure.

FIG. 40 illustrates the inhibitory effect of air, xenon and nitrogen ontyrosinase at 100 atm. pressure. This effect is due to enzyme damagefrom high pressure.

FIG. 41 illustrates that enzyme-substrate concentrations influence theresults of noble gas enhancement or inhibition, as exemplified withβ-D-glucosidase activity. S1, S2 and S3 represent three different andincreasing substrate concentrations. This result is advantageous as itmeans that existing biotechnological processes can be modified to lowerthe cost of enzyme and/or substrate or even to facilitate reactions notpresently possible.

FIG. 42 illustrates the differing effects of xenon and neon in,respectively, enhancing, then inhibiting lactate dehydrogenase at 10°C., for example. This is advantageous as it means that a given enzymemay be either enhanced or inhibited depending upon the gas selected.

FIG. 43 illustrates that even at high temperatures, the effect of thepresent invention is observed. Notably, at 60° C., α-glucosidaseactivity is enhanced by argon, nitrogen and xenon and inhibited bykrypton. Clearly, for this enzyme, argon is a potent enhancer at 60° C.

FIG. 44 illustrates the effect of xenon at 25° C. in enhancing theenzymatic activity of β-glucosidase in immobilized form.

As noted above, enzymatic activities may be regulated in accordance withthe present invention over a wide temperature range ranging from as lowas the temperature of liquid nitrogen (about -200° C.) to about 120° C.Moreover, the pressure of the gases or gas mixtures used may be as lowas an ultra-high vacuum of about 10⁻⁸ atmospheres to up to about 100atmospheres. However, it may be desirable to use even lower or evenhigher pressures. Generally, however, gas pressures of about 10⁻³ toabout 3 atmospheres are used, with gas pressures of about 10⁻² to about2 atmospheres most commonly used.

As noted above, the present invention is effective in regulatingenzymatic activity regardless of the enzyme selected and the form of theenzyme. The folowing example is provided to illustrate the effectivenessof the present invention in regulating the enzymatic activity ofimmobilized enzymes.

Protocol: Immobilized Enzymes

Theory: Same gases effects on either free or immobilized enzymes.

Gases:

1. Air

2. Xenon

Enzyme:

β-D-Glucosidase (SIGMA) No. G-0898)

β-D-Glucoside glucohydrolase EC 3.2.1.21)

From Caldocellum saccharolyticum: Recombinant (pfs)

Expressed in E. coli

Lyophilized powder

Thermostable enzyme with half-life of 38 hr at 70° C.

Unit Definition:

One unit will liberate 1.0 μmole of glucose from salicin per min at pH5.0 at 37° C.

Activity: 46 U/g solid

10.87 g solid 500 Units

Stored dessicated at 0°-5° C.

Lot# 50H0251

Substrate:

p-Nitrophenyl-β-D-Glucopyranoside (SIGMA No. N-7006)

Crystalline

Contains 2.4% solvent

Anhydrous Mol. Wt. 301.3

Stored dessicated below 0° C.

Lot# 129F-5057

Solution Preparation:

prep: May 21, 1991

Soln A: Sodium phosphate buffer pH 6.6 at 25° C.

1 T. Deionized water

141.96×0.2×187.5×1/1000=5.3 g Na₂ HPO₄

119.96×0.2×312.5×1/1000=7.5 g NaH₂ PO₄

prep: May 21, 1991

Soln B: 100 μg/mL β-D-Glucopyranoside solution in Na Phos. buffer

25 mg N-7006 diluted to 250 ml Na Phos. buffer pH

6.6 at 25° C.

prep: May 21, 1991

Soln C1: β-D-Glucosidase solution in Na Phos. buffer pH 6.6 (25 ° C.)(2.18 Units/ml)

1 g G-0898 solubilized in 21 mL Na Phos. buffer pH 6.6 at 25° C.

(For insoluble enzymes lyophilized powders, SIGMA recommends to suspendthe required amount to 5-10 mg solid/ml H₂ O and to allow briefhydration). We allowed a brief hydration (until solution appears)

400 nm

80 Pts

16s int

y_(min) =0.0

y_(max) =3.0

Blank: 2 ml Soln A+0.5 ml Soln C1

Sample: 2 ml Soln B+0.5 ml Soln C1

Files: G0898G1 . . . 4.SP

*TRIAL 2: May 22, 1991

Cell Transporter:

2 replicates

Run: Cell 1: Air

Cell 2: Air (replicate)

Cell 3: Xe

Cell 4: Xe (replicate)

PARAM: slit 1

speed 1500

Asave Y

Aprint N

CPRG: β-Glucosidase: 25° C.

400 nm

120 Pts

16s int

y_(min) =0.0

y_(max) =1.0

Blank: 2 ml Soln A+0.5 ml Soln C2

Sample: 2 ml Soln B+0.5 ml Soln C2

Files: 2G0898G1 . . . 4.SP

In order to further exemplify the present invention and the effectsobtained thereby, kinetic analyses were conducted.

Kinetic Analyses

Absorbance curve data as previously exemplified reveal differences inenzymatic activity under different gas atmospheres both in terms ofyield and in terms of rate. Yield can be calculated after equilibrium isreached by comparative curve differencing, and through formallinearization and calculation--which are also necessary for ratecalculations. Rate differences are calculated using commerciallyavailable computer programs (ENZFITTER, GRAFIT, ENZPACK, PEAKFIT) whichtransform the initial uv/vis absorbance data curve (in these examples, apower curve) into straight lines (linear regression of power curve).These lines may be expressed as a mathematical equation in which theslope is approximately the rate, and the limit Y-intercept isapproximately the yield. These data may be further treated to deriveMichaelis-Menten or other standard biochemical relationships (expressedgraphically or mathematically), from which the rate and yield may beexactly derived. The examples and figures described below representthese steps in exemplary form.

FIG. 45 illustrates uv/vis absorbance power curves for β-glucosidaseunder air at five different substrate concentrations.

Table 1 illustrates Michaelis-Menten enzyme kinetics calculations ofVmax and Km, and the rates for each reaction. Vmax is the limiting rate,Km is the Michaelis-Menten constant.

FIG. 46 and Table 2 illustrate the same as FIG. 45 and Table 1, however,for xenon reactions. It is readily apparent that the Vmax and Km forxenon are larger.

FIG. 47, Table 3, FIG. 48 and Table 4 illustrate the first-order powercurve regression rate linear transformations for the above air and xenongassed reactions, showing an approximation to the Michaelis-Menten data,wherein the Xe/Air rate relationship is in the same ratio as above.

FIG. 49, FIG. 50 and Table 5 illustrate the same first-order rateapproximation regression linearizations for all gases studied in thisrun. In this case, only the xenon showed a significant enhancement, atthe power curve analysis, but linearization clearly shows that othergases were enhancing the reaction.

FIG. 51, Table 6, FIG. 52 and Table 7 illustrate data from the first 160seconds of a single tyrosinase experiment expressed as power curves forair, then for xenon gassing. The linearized rate regression shows that,and the Michaelis-Menten calculations shown confirms that, xenon isstrongly inhibiting tyrosinase activity.

                  TABLE 1                                                         ______________________________________                                        Gas 1: Air                                                                    Enzyme Kinetics                                                               Simple weighting                                                              Reduced Chi squared = 0.0000                                                  ______________________________________                                        Variable      Value    Std. Err.                                              ______________________________________                                        V max         0.0025   0.0002                                                 Km            -3.1783  2.6341                                                 ______________________________________                                               X             Y                                                               [S]           Rates G1 Calculated                                      ______________________________________                                        1      20.0000       0.0029   0.0029                                          2      40.0000       0.0028   0.0027                                          3      60.0000       0.0025   0.0026                                          4      80.0000       0.0030   0.0026                                          5      100.0000      0.0022   0.0026                                          ______________________________________                                    

The remaining data sets are graphically represented in the Figures asindicated above.

                  TABLE 2                                                         ______________________________________                                        Gas 5: Xenon                                                                  Enzyme Kinetics                                                               Simple weighting                                                              Reduced Chi squared = 0.0000                                                  ______________________________________                                        Variable      Value    Std. Err.                                              ______________________________________                                        V max         0.0028   0.0001                                                 Km            -2.4539  1.3570                                                 ______________________________________                                               X             Y                                                               [S]           Rates G5 Calculated                                      ______________________________________                                        1      20.0000       0.0032   0.0032                                          2      40.0000       0.0029   0.0029                                          3      60.0000       0.0027   0.0029                                          4      80.0000       0.0030   0.0029                                          5      100.0000      0.0029   0.0028                                          ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        [S] = 60 micrograms/ml                                                        1st order rate equation                                                       Simple weighting                                                              Reduced Chi squared = 0.0002                                                  ______________________________________                                        Variable        Value    Std. Err.                                            ______________________________________                                        Limit           0.8021   0.0146                                               Rate constant   0.0032   0.0001                                               ______________________________________                                               X             Y                                                               Time          Abs      Calculated                                      ______________________________________                                         1     0.0000        0.0471   0.0000                                           2     15.0000       0.0777   0.0377                                           3     30.0000       0.1071   0.0737                                           4     45.0000       0.1346   0.1080                                           5     60.0000       0.1626   0.1406                                           6     75.0000       0.1890   0.1717                                           7     90.0000       0.2136   0.2014                                           8     105.0000      0.2386   0.2296                                           9     120.0000      0.2623   0.2566                                          10     135.0000      0.2849   0.2822                                          11     150.0000      0.3067   0.3067                                          12     165.0000      0.3287   0.3300                                          13     180.0000      0.3485   0.3522                                          14     195.0000      0.3691   0.3734                                          15     210.0000      0.3881   0.3935                                          16     225.0000      0.4066   0.4128                                          17     240.0000      0.4244   0.4311                                          18     255.0000      0.4414   0.4485                                          19     270.0000      0.4579   0.4652                                          20     285.0000      0.4741   0.4810                                          21     300.0000      0.4897   0.4961                                          22     315.0000      0.5044   0.5105                                          23     330.0000      0.5190   0.5242                                          24     345.0000      0.5325   0.5373                                          25     360.0000      0.5448   0.5498                                          26     375.0000      0.5569   0.5616                                          27     390.0000      0.5687   0.5730                                          ______________________________________                                    

                  TABLE 4                                                         ______________________________________                                        [S] = 60 micrograms/ml                                                        1st order rate equation                                                       Simple weighting                                                              Reduced Chi squared = 0.0014                                                  ______________________________________                                        Variable        Value    Std. Err.                                            ______________________________________                                        Limit           0.8382   0.0228                                               Rate constant   0.0045   0.0003                                               ______________________________________                                               X             Y                                                               Time          Abs [S3] Calculated                                      ______________________________________                                         1     0.0000        0.1261   0.0000                                           2     15.0000       0.1590   0.0544                                           3     30.0000       0.1928   0.1053                                           4     45.0000       0.2217   0.1529                                           5     60.0000       0.2514   0.1974                                           6     75.0000       0.2811   0.2390                                           7     90.0000       0.3085   0.2779                                           8     105.0000      0.3349   0.3143                                           9     120.0000      0.3608   0.3483                                          10     135.0000      0.3831   0.3801                                          11     150.0000      0.4065   0.4099                                          12     165.0000      0.4300   0.4377                                          13     180.0000      0.4511   0.4637                                          14     195.0000      0.4719   0.4880                                          15     210.0000      0.4940   0.5108                                          16     225.0000      0.5112   0.5320                                          17     240.0000      0.5311   0.5519                                          18     255.0000      0.5503   0.5705                                          19     270.0000      0.5675   0.5879                                          20     285.0000      0.5842   0.6042                                          21     300.0000      0.6011   0.6194                                          22     315.0000      0.6165   0.6336                                          23     330.0000      0.6313   0.6469                                          24     345.0000      0.6460   0.6593                                          25     360.0000      0.6588   0.6709                                          26     375.0000      0.6711   0.6818                                          27     390.0000      0.6834   0.6919                                          ______________________________________                                    

                  TABLE 5                                                         ______________________________________                                        Gas 1: Air                                                                    1st order rate equation                                                       Simple weighting                                                              Reduced Chi squared = 0.0002                                                  ______________________________________                                        Variable        Value    Std. Err.                                            ______________________________________                                        Limit           0.8021   0.0146                                               Rate constant   0.0032   0.0001                                               ______________________________________                                               X             Y                                                               Time          Abs G1   Calculated                                      ______________________________________                                         1     0.0000        0.0471   0.0000                                           2     15.0000       0.0777   0.0377                                           3     30.0000       0.1071   0.0737                                           4     45.0000       0.1346   0.1080                                           5     60.0000       0.1626   0.1406                                           6     75.0000       0.1890   0.1717                                           7     90.0000       0.2136   0.2014                                           8     105.0000      0.2386   0.2296                                           9     120.0000      0.2623   0.2566                                          10     135.0000      0.2849   0.2822                                          11     150.0000      0.3067   0.3067                                          12     165.0000      0.3287   0.3300                                          13     180.0000      0.3485   0.3522                                          14     195.0000      0.3691   0.3734                                          15     210.0000      0.3881   0.3935                                          16     225.0000      0.4066   0.4128                                          17     240.0000      0.4244   0.4311                                          18     255.0000      0.4414   0.4485                                          19     270.0000      0.4579   0.4652                                          20     285.0000      0.4741   0.4810                                          21     300.0000      0.4897   0.4961                                          22     315.0000      0.5044   0.5105                                          23     330.0000      0.5190   0.5242                                          24     345.0000      0.5325   0.5373                                          25     360.0000      0.5448   0.5498                                          26     375.0000      0.5569   0.5616                                          27     390.0000      0.5687   0.5730                                          ______________________________________                                    

                  TABLE 6                                                         ______________________________________                                        Gas 1: Air                                                                    Enzyme Kinetics                                                               Simple weighting                                                              Reduced Chi squared = 0.0000                                                  ______________________________________                                        Variable        Value    Std. Err.                                            ______________________________________                                        V max           0.0003   0.0003                                               Km              -17.0661 3.5059                                               ______________________________________                                               X               Y                                                             [S]             Gas 1: Air                                                                              Calculated                                   ______________________________________                                        1      10.0000         0.0018    -0.0004                                      2      20.0000         0.0019    0.0021                                       3      30.0000         0.0011    0.0007                                       4      40.0000         0.0018    0.0005                                       5      50.0000         0.0018    0.0005                                       ______________________________________                                    

                  TABLE 7                                                         ______________________________________                                        Gas 5: Xenon                                                                  Enzyme Kinetics                                                               Simple weighting                                                              Reduced Chi squared = 0.0000                                                  ______________________________________                                        Variable      Value    Std. Err.                                              ______________________________________                                        V max         0.0001   0.0003                                                 Km            -27.9623 6.3527                                                 ______________________________________                                               X              Y                                                              [S]            Gas 5: Xenon                                                                             Calculated                                   ______________________________________                                        1      10.0000        0.0007     -0.0001                                      2      20.0000        0.0019     -0.0003                                      3      30.0000        0.0019     0.0017                                       4      40.0000        0.0019     0.0004                                       5      50.0000        0.0004     0.0003                                       ______________________________________                                    

Thus, the present invention provides a method of regulating enzymaticactivity of any enzyme and in any form. Further, this regulation may beeffected over the broad temperature and pressure ranges indicated.

As noted previously, the regulated enzyme or enzymes of the presentinvention may be in an aqueous or organic solution, in immobilized form,in a dispersion or in any type of organic matrix, such as a gel, forexample. Such solutions, immobilized forms, dispersions or organicmatrices are known to those skilled in the art.

Additionally, in accordance with the present invention, a mixture ofenzymes may be regulated by inhibiting one or more enzymes therein or byenhancing one or more enzymes therein. Alternatively, it is possible toeffect regulation by both inhibiting one or more enzymes in the mixtureand enhancing one or more other enzymes therein.

Further, it is well within the skill of the artisan to utilize thepresent disclosure and guidelines set forth hereinabove to determine theoptical levels of pH, temperature, pressure, [E] and [S] for anyparticular enzyme system or mixed enzyme system of interest.

For example, for any particular enzyme system or mixed enzyme system ofinterest, optical conditions of pH, pressure, temperature, [E] and [S]may be ascertained when purchasing the enzyme or enzymes, and by usingwell known reference manuals. See, for example, the catalogues of theSigma Chemical Company for 1990 and 1991, and Enzymes by Dixon and Webb,Third Edition (Wiley, 1979). From this knowledge, the artisan can thenascertain, using the present disclosure, the optimal mixture of gases,temperature and pressure in order to obtain the desired effects inaccordance with the present invention.

Having described the present invention, it will now be apparent to oneof ordinary skill in the art that many changes and modifications can bemade to the above embodiments without departing from the spirit and thescope of the present invention.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:
 1. A method for using an enzyme to act on asubstrate therefor, wherein the enzyme activity is improved, whichmethod comprises contacting at least one enzyme selected from the groupconsisting of hydrolases, lyases, isomerases and ligases, with thesubstrate therefor, and during at least part of said contacting,contacting said at least one enzyme with an amount effective to improvesaid enzyme activity of a gas consisting essentially of a noble gasselected from the group consisting of xenon, argon, neon, krypton andmixtures thereof, at a temperature effective to improve said enzymeactivity, and at a pressure of up to about 3 atmospheres.
 2. The methodof claim 1, wherein said gas is a mixture of said noble gases.
 3. Themethod of claim 1, wherein said at least one enzyme is in solution, inimmobilized form, in a dispersion or in an organic matrix.
 4. The methodof claim 1, wherein said contacting of said at least one enzyme withsaid gas is effected at a temperature from about liquid nitrogentemperature to about 120° C.
 5. The method of claim 4, wherein saidtemperature is from about 20° C. to 60° C.
 6. The method of claim 1,wherein said at least one enzyme is contacted with said gas under apressure of from about 10⁻⁸ atmospheres to about 3 atmospheres.
 7. Themethod of claim 6, wherein said at least one enzyme is contacted withsaid gas under a pressure of from about 10⁻³ atmospheres to about 3atmospheres.
 8. The method of claim 7, wherein said at least one enzymeis contacted with said gas under a pressure of from about 10⁻²atmospheres to about 2 atmospheres.
 9. The method of claim 1, whereinsaid at least one enzyme is contacted with said gas during all of saidcontacting of said at least one enzyme with said substrate therefor. 10.The method of claim 1, wherein said enzyme is a hydrolase.
 11. Themethod of claim 1, wherein said enzyme is a lyase.
 12. The method ofclaim 1, wherein said enzyme is an isomerase.
 13. The method of claim 1,wherein said enzyme is a ligase.